NORTH   AMERICAN   MONOSTOMES 


BY 

EZRA  CLARENCE  HARRAH 

A.B.  Southwestern  College,  1913 
A.  M.  University  of  Illinois,   1919 


THESIS 

SUBMITTED  IN  PARTIAL  FULFILLMENT  OF  THE  REQUIREMENTS  FOR 

THE  DEGREE  OF  DOCTOR  OF  PHILOSOPHY  IN  ZOOLOGY  IN 

THE   GRADUATE   SCHOOL   OF  THE   UNIVERSITY  OF 

ILLINOIS,  1921 


Reprinted   from   the    ILLINOIS    BIOLOGICAL   MONOGRAPHS, 
Vol.  VII,  number  3,  pages  219-328 


NORTH   AMERICAN   MONOSTOMES 


BY 

EZRA  CLARENCF^HARRAH 

A.B.  Southwestern  Cotte"ge7  1913 
A.  M.  University  of  Illinois,    1919 


THESIS 

SUBMITTED  IN  PARTIAL  FULFILLMENT  OF  THE  REQUIREMENTS  FOR 

THE  DEGREE  OF  DOCTOR  OF  PHILOSOPHY  IN  ZOOLOGY  IN 

THE  GRADUATE   SCHOOL  OF  THE  UNIVERSITY  OF 

ILLINOIS,  1921 


Reprinted  from   the   ILLINOIS   BIOLOGICAL   MONOGRAPHS, 
Vol.  VII,  number  3,  pages  219-328 


.••>.::;-';.-"-:0-~: 


COPYRIGHT,  1922  BY  THE  UNIVERSITY  OF  ILLINOIS 
DISTRIBUTED  DECEMBER  31,1922 


TABLE  OF  CONTENTS 

Introduction 7 

Methods  of  investigation 8 

Material '  '  8 

Historical  data 10 

Species  previously  described  from  North  America 11 

New  species  described  in  this  paper 12 

Families  of  Monostomidae 13 

Key  to  families 13 

Description  of  families 14 

Cyclocoelidae  validity  of  the  older  name 14 

Diagnosis 14 

Key  to  subfamilies  and  genera 16 

Cyclocoelum 15 

Historical ( 16 

Structure  of  the  genus 20 

Key  to  species  of  cyclocoelum 34 

Description  of  species 35 

Cyclocoelum  leidyi  nov.  spec 35 

Cyclocoelum  pseudomicrostomum  nov.  spec 37 

Cyclocoelum  halli  nov.  spec 38 

Cyclocoelum  wilsoni  nov.  spec 40 

Cyclocoelum  cuneatum  nov.  spec 41 

Cyclocoelum  obscurum  (Leidy) 42 

Cyclocoelum  macrorchis  nov.  spec 44 

Cyclocoelum  triangularum  nov.  spec 46 

Cyclocoelum  mcarium  (Arnsdorff) 47 

Notocotylidae 48 

Diagnosis  of  family 49 

Key  to  subfamilies  and  genera 49 

Notocotylinae 50 

Notocotylus 50 

Notocotylus  itrbanensis  (Cort) 51 

Stages  in  the  life  history 52 

Notocotylus  quinqueserialis  (Barker  and  Laughlin) 53 

Catatropis 54 

Catatropis  filamentis  Barker 54 

Paramonostomum 55 

Paramonostomum  echinum  nov.  spec 55 

Nudocotylinae 56 

Nudocotyle  novicia  Barker 56 

Heronimidae 57 

Heronimns  chelydrae  MacCallum 57 

Collyriclidae 60 

Collyrklum  colei  Ward 60 

Diagnosis 60 

Remarks  on  the  life  history 64 


er  O  i  ii  OQ 


8  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [226 

METHODS  OF  INVESTIGATION 

The  methods  employed  in  this  study  are  those  ordinarily  used  with 
similar  material.  No  special  technique  has  been  found  necessary.  In 
general  sections  were  stained  in  toto  with  Erlich's  acid  hematoxylin  and 
counterstained  in  section  with  alcoholic  eosin.  Sections  were  cut  10  to 
20  micra  in  thickness.  Frontal,  sagittal,  and  transverse  sections  were 
used.  In  order  to  obtain  a  clearer  perception  of  more  minute  and  obscured 
parts  wax  reconstructions  were  made.  These  were  employed  particularly 
to  find  the  relationship  and  constancy  of  form  of  the  female  genital  organs. 

MATERIAL 

The  material  on  which  this  study  is  based  is  composed  of  various  collec- 
tions from  different  regions  of  the  United  States.  It  is  limited  to  that 
obtained  from  North  American  fresh  water  hosts  and  in  each  instance  is 
listed  with  the  species  description.  However  for  comparison  with  the 
Amerian  material  the  following  specimens  were  secured  from  the  sources 
indicated. 

EUROPEAN  MATERIAL 
From  the  Zoological  Museum,  Berlin 

Species  Host  Cat.  No.  Collector 

Cyclocoelum  problematicum          Totanus  glottis  2449  Ehrenberg 

Cyclocoelum  problematicum  Totanus  glottis  2455  Ehrenberg 

Cyclocoelum  problematicum          Canis  vulpecula  2454  Ehrenberg 

Cyclocoelum  ovopunctatum  1342 

Cyclocoelum  brazilianum  Scolapax-flavicepa  2494  v.  Olfers 

Cyclocoelum  tringae  2495  Ehrenberg 

Haematotrephus  similis  Himantop.  atropterus  2486  Ehrenberg 

Haematotrephus  similis  2309  Ehrenberg 

Monostomum  vanelli  Vancllus  cristatus  1326  Rudolphi 

From  the  Zoological  Museum,  University  of  Gottingen 

Cyclocoelum  (Monostomum)          Gallinula  chloropus  284  Mehlis 

mutabile  (Zed.)  Taken  at  Claustal 

Monostomum  verrucosum  Anas  bernicla  234  Mehlis 

Monostomum  attenuatum  Mergus  merganser  238  Mehlis 

Monostomum  attenuatum  Anas  fuligula  220  Mehlis 

From  the  Zoological  Museum,  University  of  Vienna 

Monostomum  mutabile  Totanus  flaviceps  IX    552 

Taken  in  Brazil 

From  the  Collection  of  Henry  B.  Ward,  University  of  Illinois 
Collyriclum  faba  Passer  domesticus  21.764      Zschokke 

Taken  in  Switzerland 

NORTH  AMERICAN  MATERIAL 

From  the  Leidy  Collection 

Cyclocoelum  leidyi  Gallinago  wilsoni  160          Leidy 

(Monostomum  mutabile 
Zeder  of  Leidy) 


227]  NORTH  AMERICAN  MONOSTOMES 

Species  Host  Cat.  No.        Collector 

Cyclocoelum  pseudomicrostomum       Fulica  amerkana  186      Leidy 

(Monostomum  mutabile 
Zeder  of  Leidy) 

From  the  collection  of  the  Army  Medical  Museum 
Cyclocoelum  obscurum  Stereolepsis  sp?  1035    Leidy 

From  the  collection  of  the  Bureau  of  Animal  Industry 

Notocotylus  urbanensis  Dafila  acuta  5772    Stiles  &  Hassall 

(Monostoma  sp.  Stiles  &  Hassall) 

Notocotylus  urbanensis  Fiber  zibethicus  5769 

(Monostoma  sp.  Stiles  &  Hassall)  5770    Stiles  &  Hassall 

Notocotylus  urbanensis  Aix  sponsa  5771    Stiles  &  Hassall 

(Monostoma  sp.  Stiles  &  Hassall) 

Notocotylus  quinqueserialis  Arvicola  riparius  5773    Stiles  &  Hassall 

(Monostoma  sp.  Stiles  &  Hassall) 

•  • .  ,jj 

From  the  Collection  of  Henry  B.  Ward,  University  of  Illinois 

Cyclocoelum  pseudomicrostomum       Wild  duck  10.41 

Cyclocoelum  cuneatum  Gallinago  delicata  08. 172 

Cyclocoelum  obscurum  Symphaemia  semipalmata  08.179 

Cyclocoelum  obscurum  (unknown)  08 . 183 

Cyclocoelum  macrorchis  Straight  billed  curlew  08 . 180 

Notocotylus  quinqueserialis  Fiber  zibethicus  15.120 

Paramonostomum  echinum  Fiber  zibethicus  21.91 

Her  animus  chelydrae  Snapping  turtle  08.176 

Emys  blandingi  12 . 161,  162,  163 

Chrysemys  marginata  N.B.  15,  21 . 760,  22 . 169 

Kinosternon  odoratus  16.425 
Cinosternum  pennsyhanicum     22.40,  41 

Graptemys  geographicus  22 . 166 

Collyriclum  colei  Passer  domesticus  11.11    L.  J.  Cole 

11.12,21.961,762 

Cyclocoelum  halli  Totanus  melanoleucus  21.90    W.  C.  Hall 

Totanus  solitarius  21 . 763  W.  C.  Hall 

Cyclocoelum  wilsoni  Gallinago  delicata  21.89    W.  C.  Hall 

Cyclocoelum  triangularum  Tringa  maculata  21.88    W.  C.  Hall 


10  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [228 


HISTORICAL   DATA 

More  than  a  century  ago  the  first  of  the  Monostomata  were  described. 
Since  that  time  many  helminthologists  have  contributed  to  the  study  of 
this  group.  Most  notable  of  the  older  authors  are  Zeder,  Rudolphi,  von 
Siebold,  Van  Beneden  and  Diesing.  In  more  recent  times  Brandes,  Stos- 
sich,  Looss,  Luhe,  Monticelli,  Kossack  and  Odhner  have  contributed 
materially  to  our  knowledge  of  the  European  forms. 

Apart  from  the  work  of  Goeze  (1782)  who  described  two  species  which 
he  believed  to  have  only  one  sucker  and  that  of  Schrank  (1788)  which  was 
a  mere  catalogue  of  species,  Zeder  (1800,  1803)  was  the  first  to  establish 
this  group.  In  1800  he  created  the  genus  Monostoma  based  on  five  species; 
Monostoma  ocreatum,  and  Monostoma  bombynae  which  have  since  been 
removed  to  the  distomes;  Monostoma  verrucosum  a  No  toco  ty  lid;  and 
Monostoma  prismaticum  and  Monostoma  mutabile  which  are  now  trans- 
ferred to  the  genus  Cyclocoelum.  Rudolphi  in  his  Synopsis  Entozoorum 
served  in  the  early  organization  of  the  group.  While  a  number  of  species 
were  imperfectly  known  at  this  time  it  was  not  until  the  work  of  von 
Siebold  (1835)  was  published  that  the  anatomy  of  these  worms  was  clearly 
understood.  In  this  work  the  author  gave  a  good  description  of  Monostoma 
mutabile  Zeder  along  with  the  early  stages  of  the  life  history  as  shown  in 
the  development  of  the  egg  before  it  is  discharged  from  the  uterus.  Diesing 
(1850)  reorganized  the  genus  including  all  species  described  up  to  this 
time.  Following  this  Van  Beneden  (1861)  reviewed  the  anatomy  of 
Monostomum  mutabile  and  added  a  description  of  the  anatomy  of  Mono- 
stomum  verrucosum  Frolich  with  a  study  and  description  of  a  cercaria  which 
he  believed  to  be  the  larval  form  of  this  species.  The  next  important 
contributions  to  the  knowledge  of  this  group  were  those  of  Monticelli 
(1892)  in  which  he  gave  a  complete  account  of  the  genus  Notocotyle  Dies- 
ing and  in  a  second  paper  in  the  same  year  a  similar  account  of  Monosto- 
mum cymbium  Diesing.  Closely  following  these  was  the  Revision  of  Brandes 
(1892)  in  which  he  proposed  the  new  genus  Cyclocoelum  to  include  Mono- 
stomum mutabile,  M.  flavum,  M.  arcuatum,  M.  tringae  and  M.  ellipticum. 

In  more  recent  time  the  work  of  Stossich  (1902),  Odhner  (1905,  1907) 
and  Kossack  (1911)  stands  out  as  important  contributions  to  the  knowl- 
edge of  this  group.  Looss  and  Luhe  have  likewise  had  a  share  in  the 
organization  of  the  group  as  a  unit.  The  most  recent  European  work  on 
members  of  this  group  is  that  of  Jegen  (1917)  in  which  he  presents  data  on 
the  life  history  and  relationship  of  Collyriclum  faba  Bremser. 


229\  NORTH  AMERICAN  MONOSTOMES  11 

In  North  America  little  has  been  done  on  this  group  of  trematodes  and 
aside  from  the  systematic  arrangement  of  species  by  Pratt  (1902)  and  the 
descriptive  key  of  Ward  (1918)  only  isolated  descriptions  of  species  have 
appeared.  The  earliest  report,  of  species  which  have  been  assigned  to  this 
group  are  those  of  Joseph  Leidy  (1856-1895)  the  descriptions  of  which  are 
so  meager  that  some  of  the  forms  must  remain  as  species  inquirendae. 

MacCallum  (1902)  found  and  described  Heronimus  chelydrae  from  the 
lungs  of  the  snapping  turtle.  Barker  and  Parsons  fifteen  years  later  re- 
described  this  form  without  reference  to  the  work  of  MacCallum  under  the 
name  Aorchis  extensus.  Barker  and  Laughlin  (1911)  described  Notocotyle 
quinqueserialis  from  the  intestine  of  Fiber  zibethicus  and  later  Barker  (1916) 
described  from  the  same  host  the  new  genus  and  species  Nudocotyle  nomcia. 
These  with  the  report  by  Cole  of  Monostomafaba  (later  named  Collyricum 
colei  by  Ward)  are  the  major  items  from  North  America.  More  recently 
Stunkard  (1919)  has  shown  that  Heronimus  chelydrae  of  MacCallum  and 
Aorchis  extensus  of  Barker  and  Parsons  are  identical,  and  Tyzzer  (1918) 
from  the  study  of  Collyriclum  colei  Ward  and  comparison  of  it  with  the 
description  of  Collyriclum  faba  Bremser  by  Kossack,  provisionally  regards 
them  as  identical.  Tyzzer's  paper  affords  a  detailed  account  of  the 
anatomy  of  this  species  and  a  study  of  the  maturation,  fertilization  and 
development  of  the  miracidia  within  the  eggs.  His  views  regarding  the 
identity  of  the  two  forms  are  discussed  in  detail  later  (p.  62-65). 

SPECIES  PREVIOUSLY  DESCRIBED  FROM  NORTH  AMERICA 

Most  descriptions  of  North  American  species  of  this  group  are  inade- 
quate and  as  a  result  of  this  it  is  impossible  to  determine  with  any  degree 
of  accuracy  their  rightful  systematic  position  without  re-examination  of 
the  material.  This  has  been  lost  in  a  number  of  cases  and  in  other  instances 
all  effort  to  locate  certain  specimens  has  proved  futile.  The  following  list 
is  an  attempt  to  bring  together  all  references  to  date  on  the  species  pre- 
viously described  from  North  American  fresh  water  hosts.  Names  in- 
dented represent  later  descriptions  of  the  same  form  arranged  in  chrono- 
logical order. 

Monostomum  ornatum  Leidy  1856:43 

Monostomum  ornatum  Brandes  1892:504-510 
Haematoloechus?  Stafford  1902:724 

Monostomum  incommodum  Leidy  1856:43 
Distoma  oricola  Leidy  1884:47 
Distoma  oricola  Leidy  1891:414 

Monostomum  affine  Leidy  1858:43 

Notocotyle?  affine  (Leidy  1858)  Barker  1916:183 


12  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [230 

Monostomum  spatulatum  Leidy  1858:111 

Monostomum  spathulatum  Leidy  of  Diesing  1859:426 

Monostomum  asperum  Vaillant  (nee.  Nitzsch)  1863:6-7;  1863:347-348 
Monostomulum  asperum  Vaill.  of  Brandes  1892:504-511 
Monostomum  aspersum  Vaill.  of  Pratt  1902:966 
Monostomum  aspersum  Vaill.  of  Pratt,  Ward  1918:382 

Monostomum  mutabile  Zeder  of  Leidy  1885:9 
Cycloccelum  leidyi  nov.  spec,  of  this  paper 

Monostomum  obscurum  Leidy  1887:24 

Cyclocoelum  obscurum  (Leidy)  of  this  paper 

Monostomum  amiuri  Stafford  1900:402 

Cyclocoelum  mcarium  (Arnsdorff  1908)  Kossack  1911:518 
Monostomum  mcarium  Arnsdorff  1908:362 

Notocotyle  quinqueserialis  Barker  and  Laughlin  1911:261-274 

Catatropis  filamentis  Barker  1915:  PL  I,  fig.  6 
Catatropis  fimbriata  Barker  1915:190 

Nudocotyle  nomcia  Barker  1916:175-184 

Heronimus  chelydrae  MacCallum  1902:632-636 

Aorchis  extensus  Barker  and  Parsons  1914:193—194 

Cottyriclum  colei  Ward  1917:2-3 

Monostoma  faba  Cole  1911:42-48 
Collyriclum  faba  Tyzzer  1918:267-292 

NEW  SPECIES  DESCRIBED  IN  THIS  PAPER 

Cyclocoelidae 

Cyclocoelinae 

Cyclocoelum  leidyi  nov.  spec. 
Cyclocoelum  pseudomicrostomum  nov.  spec. 
Cyclocoelum  macrorchis  nov.  spec. 
Cyclocoelum  wilsoni  nov.  spec. 
Cyclocoelum  halli  nov.  spec. 
Cyclocoelum  triangularum  nov.  spec. 
Cyclocoelum  cuneatum  nov.  spec. 
Notocotylidae 

Notocotylinae 

Notocotylus  urbanensis  (Cort) 

(Cercaria  only  known  previously) 
Paramonostomum  echinum  nov.  spec. 


231]  NORTH  AMERICAN  MONOSTOMES  13 


FAMILIES  OF  MONOSTOMIDAE 

Altho  in  another  section  of  this  paper  the  monostomes  are  shown  to 
be  more  closely  related  to  other  groups  than  to  each  other  it  is  thought 
best  to  preserve  the  group  classification  until  further  evidence  is  secured 
which  definitely  proves  the  suggested  relationship.  For  this  reason  the 
key  to  the  monostome  families  is  included  and  it  is  expected  to  serve  only 
for  the  rapid  determination  of  specimens  rather  than  to  furnish  full  diag- 
nostic characters. 

KEY  TO  FAMILIES 

1  (2)  Intestinal  crura  anastomosing  in  the  posterior  end 

Family  Cyclocoelidae 

2(1)  Intestinal  crura  ending  blindly  near  the  posterior  end 3 

3(4)  Testes  lateral  to  crura Family  Notocotylidae 

4(3)  Testes  within  crura 5 

5(6)  Excretory  pore  posterior  and  terminal ....  Family  Collyriclidae 
6(5)  Excretory  pore  dorsal;  in  anterior  body  half .  Family  Heronimidae 


14  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [232 


DESCRIPTION  OF  FAMILIES 

Validity  of  the  older  name. — The  question  raised  by  Liihe  (1901) 
regarding  the  use  by  Looss  (1899)  of  the  family  name  Monostomidae 
Cobbold  1866  [erroneously  credited  to  Monticelli  by  Ltihe  (1901)  and  by 
Stossich  (1902)]  without  a  type  genus  Monostomum  and  the  extended 
discussion  of  Looss  (1902)  is  a  needless  one  if  the  rules  of  the  International 
Code  be  applied.  Article  V  of  this  code  deals  specifically  with  the  family 
name  which  by  the  acceptance  of  the  genus  name  Cyclocoelum  becomes 
Cyclocoelidae. 

CYCLOCOELIDAE  Kossack  1911 

Diagnosis. — Endoparasitic  trematodes  of  large  to  middle  sized  muscu- 
lar bodies.  Mouth  opening  terminal  or  subterminal  surrounded  by 
muscular  sucker  usually  much  reduced.  Ventral  acetabulum  sometimes 
present,  pharynx  large,  muscular;  esophagus  long.  Intestinal  crura 
simple  or  possessing  internal  ceca,  anastomosing  in  the  posterior  end  of 
the  body.  Excretory  bladder  between  posterior  intestinal  arch  and  end 
of  body  with  median  dorso-terminal  pore.  Genital  pore  median,  usually 
ventral  to  pharynx.  Copulation  organs  present,  well  developed;  seminal 
vesicle  in  cirrus  pouch.  Vitellaria  in  general  lying  between  body  wall  and 
intestinal  crura,  sometimes  surrounding  the  latter.  Genital  glands  between 
intestinal  crura,  simple  or  lobed,  forming  the  points  of  a  triangle.  Laurer's 
canal  wanting;  receptaculum  seminis  present.  Uterus  strongly  developed 
lying  in  more  or  less  regular  folds  between  intestinal  crura  over  which  they 
sometimes  extend,  usually  filling  entire  space  between  crura.  Eggs  numer- 
ous, without  polar  filament,  usually  containing  well  developed  miracidia 
with  characteristic  double  eye  spots. 

Parasitic  in  body  cavity,  lungs  and  nasal  cavities  of  water  birds. 

Type  and  only  American  genus  Cyclocoelum.  Other  genera  Haemato- 
trephus,  Hyptiasmus,  Typhlocoelum,  Tracheophilus,  Ophthalmophagus, 
Spaniometra  and  Bothriogaster. 

The  foregoing  diagnosis  differs  from  that  of  Kossack  in  noting  that  an 
oral  sucker  and  a  receptaculum  seminis  have  been  found  in  two  genera  of 
this  family,  namely  Cyclocoelum  and  Haematotrephus.  In  the  genus 
Cyclocoelum  these  organs  have  been  found  in  the  species  described  in  this 
paper  as  well  as  in  the  following  European  species:  Cyclocoelum  problema- 
ticum  Stoss.,  Cyclocoelum  owpunctatum  Stoss.,  Cyclocoelum  brazilianum 
Stoss.,  and  in  Cyclocoelum  tringae  (Brandes)  as  well  as  in  Haematotrephus 
similis  Stoss. 


233]  NORTH  AMERICAN  MONOSTOMES  15 

During  the  study  of  the  Cyclocoelidae  and  the  attempt  to  prepare  a 
key  the  writer  was  impressed  with  the  segregation  of  the  genera  into  dis- 
tinct groups.  These  groups  are  here  designated  as  sub-families.  The  group 
composed  of  Cyclocoelum,  Haematotrephus  and  Hyptiasmus  are  according 
to  this  grouping  left  in  the  sub-family  Cyclocoelinae  created  by  Stossich 
(1902)  for  the  entire  group.  A  second  group  is  that  formed  by  Typhlocoe- 
lum  Stossich  and  Tracheophilus  Skrjabin  (1913)  which  on  the  basis  of  the 
strongly  developed  vitellaria  and  diverticula  of  the  intestine  deserve  rank 
as  a  distinct  sub-family  to  which  I  desire  to  assign  the  name  Typhlocoeli- 
nae.  As  stated  in  a  later  section  of  this  paper  Cohn  (1904)  would  ally  this 
group  with  the  Fasciolidae  on  the  basis  of  a  rudimentary  sucker  found  in 
Typhlocoelum  flavum  (Mehlis).  A  third  group  is  that  formed  by  Ophthal- 
mophagus  and  Spaniometra  and  is  based  on  the  position  of  the  ovary  in 
the  intestinal  arch  with  the  testes  anterior  thereto,  and  on  the  position 
of  the  vitellaria  which  in  these  genera  are  ventral  to  the  intestine.  Bothrio- 
gaster  is  also  placed  in  this  group  although  it  presents  some  striking 
differences,  especially  with  respect  to  the  vitellaria  which  in  this  genus  are 
markedly  like  those  of  Cyclocoelum.  However  with  respect  to  the  repro- 
ductive glands  it  conforms  more  nearly  to  Spaniometra.  Other  peculiar- 
ities of  this  genus  will  be  discussed  elsewhere  in  this  paper. 

KEY  TO  SUB-FAMILIES  AND  GENERA 

1(11)  Ovary  between  testes  or  on  a  level  with  posterior  testis 2 

2(8)  Intestinal  crura  without  diverticula 

Sub-family  Cyclocoelinae  Stossich  1902 3 

3(6)  Right  and  left  sides  of  vitellaria  separated  at  posterior  end. . .  .4 
4(5)  Uterus  loosely  folded;  long  loops  surrounding  genital  glands.  .  . . 

Haematotrephus  Stossich  1902 

5(4)  Uterus  compact;  loops  short  not  surrounding  genital  glands.  .  .  . 

; Cyclocoelum  Stossich  1902 

6(3)  Right  and  left  sides  of  vitellaria  continuing  into  one  another  at 

posterior  end 7 

7        Uterine  loops  extending  laterally  over  intestinal  crura  and 

vitellaria  to  body  wall Hyptiasmus  Kossack  1911 

8(2)  Intestinal  crura  with  distinct  diverticula 

,  ^ Sub-family  Typhlocoeline  ....  9 

9(10)  Testes  strongly  lobed Typhlocoelum  Stossich  1902 

10(9)     Testes  round Tracheophilus   Skrjabin   1913 

11(1)     Ovary  posterior  to  testes,  situated  in  intestinal  arch 

Sub-family  Ophthalmophaginae  ....  12 

12(15)  Vitellaria  ventral  to  crura 13 

13(14)  Testes  in  posterior  body  half . Ophthalmophagus  Stossich  1902 
14(13)  Testes  in  anterior  body  half Spaniometra  Kossack  1911 


16  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [234 

15(12)  Vitellaria  lateral  to  crura 

Ventral  acetabulum  conspicuously  developed 

Bothriogaster  Fuhrman  1904 

Up  to  the  present  the  only  genus  in  this  family  represented  in  North 
America  is  Cyclocoelum  and  for  this  reason  the  other  genera  are  not  dealt 
with  in  the  following  pages. 

CYCLOCOELUM 

Historical. — The  question  of  the  type  for  this  genus  is  indeed  a  com- 
plicated one  and  as  Stiles  (1908)  has  said  "well  represents  a  ship  without 
a  rudder."  Liihe  accepts  the  designation  of  Hoyle  (1888)  and  takes  issue 
with  Looss  who  by  elimination  accepts  Monostomum  prismaticum  as  type. 
Stiles  (1908)  presents  a  third  view  in  which  he  says  that  the  name  Mono- 
stomum is  a  synonym  to  Festucaria  by  priority  rule,  since  Zeder  deliber- 
ately renamed  the  genus  Festucaria  Schrank  (1788). 

A  critical  study  of  the  literature  involved  brings  to  light  certain  facts 
on  this  point  which  seem  to  the  writer  to  be  worthy  of  space  here.  The 
name  Festucaria  was  proposed  by  Schrank  (1788)  for  two  species  Festu- 
caria anatis  and  Festucaria  strigis.  These  species  were  described  by  Goeze 
(1782)  in  Klasse  II  of  his  family  (genus)  Planaria  as  "rundlichte  oder 
walzenformige  Plattwurm"  of  which  he  says  there  are  two  genera.  Only 
one  of  them  is  of  concern  here  and  is  described  by  Goeze  (1782:173-174)  as 
having  a  single  mouth,  ("mit  einfacher  Miindung"). 

From  the  context  of  the  description  one  is  led  to  believe  that  these 
worms  were  collected  by  Goeze  since  he  says,  "Ich,  *  *  *  habe  sie  nur 
in  zwo  Arten  von  Vogeln  gefunden;  in  einer  zahmen  Ente,  und  in  einer 
grauen  Weideneule."  He  follows  this  with  a  description  of  the  worms  in 
situ  as  well  as  when  he  placed  the  intestine  of  the  host  in  water  where  the 
worms  "loosed  themselves/' 

The  type  of  the  genus  Festucaria  becomes  by  page  precedence  Festu- 
caria anatis  Schrank  (1788).  This  purports  to  be  the  same  worm  described 
by  Goeze  (1782:174)  as  follows: — "In  den  Dedarmen  einer  Ente  sassen 
hin  und  wieder  kleine  gelbliche  Knotgen.  Da  ich  einige  abnehmen  wollte, 
merkte  ich,  dass  sie  vest  anklebten.  Als  ich  sie  ins  Wasser  brachte,  gaben 
sie  sich  los,  und  ich  erkannte  sie  fur  rundlichte  Plattwiirmer  mit  einer 
Miindung."  The  description  of  his  figure  9  plate  13  adds  "(a)  die  einfache 
Miindung  mit  2  Punkten;  (b)  eine  Art  von  Maul  dariiber."  From  the 
description  and  the  figures  this  appears  to  be  the  crown  of  spines  which 
Goeze  mistook  for  a  mouth. 

The  description  of  Schrank  (1788),  based  on  Goeze  (1782),  runs  as 
follows: — 

Splitterwurm — Festucaria 

Ein  langlichter,  einformiger  Wurm  vorne  mit  einer  einzigen  Sauge- 
miindung. 


235]  NORTH  AMERICAN  MONOSTOMES  17 

"Enten  Sp.  54,  Cylindri-formed,  columnar,  walzenformig."  "Zween 
erhabene  Punkte  in  der  Mundoffnung,  Festucaria  anatis."  "Goeze  Eingew. 
174  tab.  13,  figs.  8-11;  in  Enten." 

Gmelin  (1790)  classifies  the  same  worm  as  Fasciola  anatis.  Zeder  (1800) 
renames  the  genus  Festucaria,  Monostoma,  and  includes  under  the  name 
the  following  species; 

Monostoma  elaphi 

Monostoma  prismaticum 

Monostoma  ocreatum 

Monostoma  mutabile 

Monostoma  verrucosum 

Monostoma  bombynae 

In  the  same  work  the  species  of  Schrank  (Festucaria  anatis}  (Fasciola  of 
Gmelin)  is  described  as  an  Echinostome  (Distoma  anatis).  Rudolphi  (1801) 
recognized  the  same  genus  Festucaria  Schrank  with  Monostoma  Zeder  as 
a  synonym  and  later  in  the  same  paper  (p.  62)  stated  that  he  permits  the 
name  Festucaria  to  stand  even  though  Zeder  had  proposed  a  new  one. 
This  name  he  retained  until  1809  when  he  rejects  it  for  the  denomination 
of  Zeder  which  he  says  "omnino  praeferenda  sit."  In  his  later  paper 
(1819)  Rudolphi  still  adhered  to  the  genus  name  of  Zeder.  Subsequent  to 
this  time  helminthologists  have  accepted  without  comment  the  genus 
Monostoma  of  Zeder.  Consequently  Hoyle  (1888)  designated  Monostoma 
mutabile  as  type  of  this  genus.  Four  years  later  Brandes  (1892)  in  his 
Revision  der  Monostomiden  grouped  together  what  he  believed  to  be 
members  of  this  genus,  "als  gute  Arten,"  Monostoma  mutabile  Zeder,  M. 
flavum  Mehlis,  M .  arcuatum  Brandes,  M.  tringae  Brandes  and  M.  ellipti- 
cum  Rudolphi  and  suggested  their  separation  from  the  remaining  species 
under  the  name  Cyclocoelum  with  the  following  diagnosis:  "Diese  flinf 
Spezies  scheinen  ihrer  Organisation  und  Lebensweise  nach  zusammenzu- 
gehoren,  jedenfalls  die  ersten  4,  die  sammtlich  in  der  Leibes-  oder  Infra- 
orbital-hohle  von  Wasservogeln  schmarotzen,  wahrend  M.  ellipticum  in 
der  Lunge  von  Rana  maculata  gefunden  wurde,  *  *  *  .  Die  Enden  der 
Darmschenkel  mit  einander  verschmelzen,  sodass  der  Darmtractus  einem 
Ring  darstellt."  Looss  (1899)  accepted  the  revision  of  Brandes  and 
named  M .  mutabile  as  type  of  the  genus  of  Brandes.  Later  in  the  same 
notable  work  the  author  used  the  term  Monostomidae  to  characterize  a 
certain  group  of  worms.  But  his  contemporary  Luhe  (1900)  in  a  re- 
view of  the  work  of  Looss  objected  on  the  ground  of  the  nomenclature  law 
to  the  use  of  the  family  name  Monostomidae  without  a  type  genus  Mono- 
stoma and  called  attention  to  the  priority  of  the  "vollig  verschollenen" 
genus  Festucaria  Schrank.  One  year  later  Looss  (1901)  in  explanation 
and  confirmation  of  his  earlier  work  showed  by  elimination  that  Mono- 
stomum  prismaticum  is  type  of  the  genus  Monostoma  Zeder.  In  regard  to 


18  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [236 

the  right  of  priority  of  Festucaria  Schrank  he  stated  that  he  found  no 
reason  to  call  back  from  oblivion  that  absolutely  meaningless  name. 
"Ich  habe  mich  bisher  nicht  veranlasst  gef  iihlt,  diesen  auch  mir  bekannten, 
aber  in  der  That  ganzlich  der  Vergessenheit  anheimgefallenen  und  prak- 
tisch  absolut  bedeutungslosen  Namen  wieder  ins  Leben  zuriickzurufen; 
ich  empfinde  dafiir  auch  heute  noch  keine  Neigung  und  tiberlasse  deshalb 
die  Entscheidung  der  Frage  mit  Vergniigen  denjenigen,  die  sich  mehr 
dafiir  interessieren."  Liihe  continued  the  discussion  on  the  basis  of  the 
priority  of  Festucaria  Schrank  and  the  deliberate  renaming  of  Zeder.  He 
stated,  however,  that  he  believes  Festucaria  anatis  Schrank  (based  on  Goeze 
1782,  Taf.  13,  Figs.  8-11)  to  be  Echinostomum  echinatum.  However  Liihe 
continued  to  use  the  genus  name  Monostoma  Zeder. 

Stossich  (1902)  accepted  Monostoma  mutabile  Zeder  (1800)  as  the 
earliest  record  of  the  group  and  approved  its  removal  by  Brandes  (1892) 
to  the  genus  Cyclocoelum.  He  does  not  consider  the  priority  of  Festucaria 
or  the  renaming  by  Zeder  (1800)  but  Zeder  says  distinctly  that  Schrank 
(1788)  placed  those  worms  with  one  sucker  in  a  genus  under  the  name 
Festucaria  and  that  he  (Zeder)  in  conformance  to  the  German  system  of 
nomenclature  wished  to  introduce  the  Greek  term  Monostoma  which  he 
considered  a  more  appropriate  and  characteristic  name. 

Kossack  (1911)  cited  the  positions  of  Hoyle,  Liihe,  Looss  and  Stiles 
previously  mentioned;  he  then  avoids  the  real  situation  by  accepting  only 
the  more  generally  recognized  works  and  thus  believes  himself  dealing 
with  a  necessity,  and  also  to  be  in  full  accord  with  the  law  of  priority. 
On  this  basis  he  omits  from  the  discussion  the  genus  name  Festucaria  and 
substitutes  for  the  old  name  Monostoma  the  more  significant  name 
Cyclocoelum. 

It  seems  to  the  writer  that  the  case  at  hand  is  clearly  covered  by 
Article  32  of  the  International  Rules  of  Zoological  Nomenclature;  and 
after  a  careful  study  of  the  case  the  writer  is  led  to  accept  Stiles'  view  and 
to  abide  by  the  ruling  of  the  International  Commission  according  to  which 
the  genus  Monostoma  Zeder  (1800)  becomes  a  synonym  of  Festucaria 
Schrank  (1788).  The  fact  that  Zeder  did  not  include  the  original  species, 
Festucaria  anatis,  in  his  genus  does  not  affect  the  case  since  the  genus 
name  would  remain  with  the  type  species;  hence  the  redescribing  of  this 
form  by  Zeder  under  the  name  Distoma  anatis  does  not  change  the  case 
since  in  that  event  Festucaria  falls  with  Monostoma  into  synonomy.  Then 
Festucaria  strigis  having  been  removed  to  the  genus  Strigea,  whether 
Festucaria  anatis,  is  a  distome  (Zeder  1800),  or  an  echinostome  (Zeder 
1803,  Rudolphi  1809,  and  Liihe  1901),  the  case  remains  the  same  and  can 
be  analyzed  only  as  a  direct  renaming  of  the  original  form.  Accordingly 
the  species  of  Monostoma  Zeder  fall  in  the  genus  Festucaria  Schrank  1788. 
The  type  is  clearly  Festucaria  anatis. 


237]  NORTH  AMERICAN  MONOSTOMES  19 

The  opinion  expressed  by  Liihe  (1901)  that  he  believes  Festucaria  ana- 
tis  to  be  an  echinostome,  is  indeed  not  a  new  view  for  in  fact  it  is  suggested 
in  the  description  of  Goeze  when  he  describes  the  orifice  as  having  above  it 
a  sort  of  a  mouth.  As  was  mentioned  earlier  in  this  work  Goeze  probably 
erroneously  described  the  crown  or  ring  of  spines  for  the  mouth.  Also 
his  description  of  the  worms  in  situ  in  the  intestine  of  a  domestic  duck 
suggests  the  probability  of  an  echinostome.  Zeder  (1800)  evidently 
recognized  the  distome  nature  of  these  worms  for  he  described  in  his 
group  Echinis  under  the  name  Distoma  anatis  worms  which  he  terms 
identical  with  Cucullanus  conoideus  Bloch  (1782),  Planaria  enten  sp. 
Goeze  (1782),  Festucaria  anatis  Schrank  (1788)  and  Fasciola  anatis  Gme- 
lin  (1790).  Characteristic  points  of  his  description  are  the  large  aceta- 
bulum  and  the  ring-like  swelling  around  the  head  armed  with  spines. 
In  1803  this  worm  was  described  by  the  same  author  as  Distoma  echinatum. 
Rudolphi  (1809)  described  Cucullanus  conoideus  Bloch,  Planaria  (teres 
poro  simplici)  Goeze,  Fasciola  anatis  Gmelin,  Festucaria  anatis  Schrank, 
Distoma  anatis  Zeder  (1800)  and  Distoma  echinatum  Zeder  (1803)  as  identi- 
cal. Likewise  Diesing  (1850)  and  Baird  (1853)  interpret  Festucaria  anatis 
as  identical  with  Distoma  echinatum.  This  with  the  opinion  of  Liihe 
already  given  appears  to  be  sufficient  evidence  to  determine  the  probably 
Echinostome  nature  of  Festucaria  anatis  Schrank.  In  any  event  the  species 
described  by  Zeder  (1800)  as  Monostoma  mutabile  which  we  now  know  as 
Cyclocoelum  mutabile  is  quite  strikingly  different  anatomically  and  hence 
clearly  not  closely  related  to  Festucaria  anatis  based  on  the  opinions  of  Zeder 
(1800,  1803),  Rudolphi  (1809,  1819),  and  Luhe  (1901).  From  a  study  of 
the  literature  the  writer  is  in  agreement  with  the  opinion  of  Liihe,  Rudolphi 
and  Zeder  that  Festucaria  anatis  is  probably  Echinostomum  echinatum 
Rud.  (1809).  Whether  these  authors  studied  the  same  material  can  be 
only  a  matter  of  conjecture. 

An  additional  fact,  however,  is  furnished  by  our  present  knowledge  of 
the  normal  habitat  of  these  worms  which  with  few  exceptions  are  confined 
to  partially  closed  cavities  of  the  body,  the  infraorbital  sinus,  and  areal 
sacs  for  Cyclocoelum  and  Hyptiasmus,  and  the  trachea  for  Typhlocoelum. 
As  has  been  previously  noted  the  habitat  of  Festucaria  anatis  is  the  intes- 
tine of  a  domestic  duck. 

The  genus  Cyclocoelum  Brandes  (1892)  was  formulated  to  include  the 
following  species  Monostoma  mutabiley  M.  flavum,  M.  arcuatum,  M. 
tringae,  and  M.  ellipticum  with  the  following  description:  first  four  species 
collected  from  the  body  cavity  and  infraorbital  sinus  of  water  birds  the 
fifth  Monostoma  ellipticum,  from  the  lungs  of  Rana  maculata,  with  intes- 
tinal crura  anastomosing  in  the  posterior  end. 

In  the  acceptance  of  the  genus  name  Cyclocoelum  Brandes  (1892)  the 
writer  realizes  that  he  is  subject  to  criticism  on  account  of  the  genus 


20  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [238 

Cyclocoela  Dujardin  (1845)  and  in  view  of  this  fact  calls  attention  to  the 
recommendation  of  the  International  Zoological  Commission  in  the  Inter- 
national Code  which  reads: — "It  is  well  to  avoid  the  introduction  of  new 
generic  names  which  differ  from  generic  names  already  in  use  only  in  ter- 
mination or  in  a  slight  variation  in  spelling  which  might  lead  to  confusion. 
But  once  introduced,  such  names  are  not  to  be  rejected  on  this  account." 

Structure  of  the  Genus 

The  description  of  Stossich  (1902)  states  that  these  worms  are  covered 
with  spines  which  that  author  interprets  of  sufficient  importance  to  be  a 
specific  characteristic.  Although  Zeder  (1803)  observed  these  granula- 
tions he  was  not  able  to  determine  their  real  nature  and  suggests  that  they 
are  either  cellular  structures  or  glands  underlying  the  thin  cuticula.  It 
was  not  until  the  work  of  Fuhrmann  (1904)  was  published  that  the  true 
nature  of  these,  which  are  really  pits  became  known.  This  author  de- 
scribed and  figured  these  pits  as  found  on  the  ventral  surface  of  Bothrio- 
gaster  variolaris  and  stated  that  he  has  observed  similar  depressions  on 
both  the  dorsum  and  venter  of  Cyclocoelum  mutabile.  However,  he  raises 
the  question  whether  these  are  not  a  product  of  preservation.  Kossack 
(1911)  verified  the  work  of  Fuhrmann  by  similar  observations  on  several 
species  belonging  to  at  least  three  distinct  genera  of  this  family.  He  sup- 
ported the  view  of  Fuhrmann  as  to  their  origin  and  added  as  evidence  of 
their  nonexistence  in  living  material  that  the  authors  who  had  opportunity 
to  study  living  material — notably  von  Siebold  and  Van  Beneden — did  not 
mention  their  presence. 

There  can  be  no  doubt  that  Zeder  (1800,  probably  also  1803)  made 
observations  on  living  material.  That  the  particular  observation  men- 
tioned above  was  made  from  living  material  of  course  is  only  a  matter  of 
conjecture.  It  is  evident,  however,  that  at  least  one  author  who  studied 
living  material  did  observe  these  pits.  Hence  the  lack  of  mention  by  von 
Siebold  and  Van  Beneden  is  not  sufficient  evidence  to  prove  their  non- 
existence  in  living  material. 

That  the  state  of  contraction  at  the  time  of  fixation  is  responsible  for 
the  degree  of  depth  and  apparent  frequency  of  these  pits  remains  unques- 
tioned. But  unless  they  occur  in  the  living  specimen  it  would  be  impos- 
sible to  find  them  so  regularly  in  preserved  material.  In  addition  if  they 
are  artifacts  of  preservation  one  would  expect  to  find  them  in  other  trema- 
tides  of  similar  size  and  structure. 

While  the  writer  has  not  had  opportunity  to  study  living  Cyclocoelidae 
he  has  found  the  above  mentioned  "Griibchen"  of  Kossack,  the  "ovale 
depressionen"  of  Fuhrmann,  constantly  in  more  than  one  hundred  and 
fifty  specimens  belonging  to  at  least  nine  species  of  the  genus  Cyclocoelum 
and  in  Haematotrephus  similis.  While  in  the  study  of  more  than  a  hundred 


239]  NORTH  AMERICAN  MONOSTOMES  21 

specimens  of  Heronimus  chelydrae  MacCallum  (1902)  both  living  and  pre- 
served not  a  single  instance  has  been  found.  For  these  reasons  the  writer 
feels  safe  in  saying  that  these  pits  are  characteristic  of  the  living  animal 
and  are  only  emphasized  by  the  state  of  contraction  at  the  time  of  preser- 
vation. The  various  worms  being  fixed  in  different  states  of  contraction 
would  consequently  show  these  pits  more  conspicuously  in  the  more  con- 
tracted specimens. 

The  body  wall  is  composed  of  at  least  five  layers.  From  outside  inward 
they  are  as  follows,  cuticula,  basement  membrane,  circular  muscle,  longi- 
tudinal muscle,  and  epithelium  (Fig.  25).  These  compose  what  is  com- 
monly known  as  the  dermomuscular  sac.  The  disposition  of  the  parts  of 
the  dermomuscular  sac  of  this  group  agrees  in  most  respects  with  the  inter- 
pretation of  Monticelli  (1888)  and  Blochmann  (1896).  It  differs  however 
from  the  observation  of  Fuhrmann  (1904)  in  which  he  says  that  the  body 
musculature  is  differentiated  into  outer  longitudinal,  inner  circular  muscle 
layers  and  inside  of  this  the  layer  of  bands  of  diagonal  muscles,  in  that 
the  outer  muscle  layer  is  formed  by  circular  muscles  (Fig.  25).  The  single 
statement  of  Fuhrmann  mentioned  above  is  so  strikingly  different  from 
all  comprehensive  works  on  this  subject  that  the  writer  is  lead  to  believe 
that  it  is  a  lapsus  calami  and  that  in  reality  the  muscle  layers  of  Bothrio- 
gaster  variolaris  are  identical  with  those  of  other  trematodes. 

Zeder  (1803)  states  that  these  worms  have  a  single  sucker  on  the  for- 
ward end.  His  description  of  this  organ  is  scanty  and  lacks  the  points 
which  distinguish  the  sucker  from  the  pharynx  so  that  one  is  lead  to  believe 
in  the  light  of  present  knowledge  that  he  interpreted  the  pharynx  in  the 
Cyclocoelidae  to  be  the  same  as  the  sucker  in  the  Notocotylidae.  Von 
Siebold  (1835),  the  first  to  give  a  clear  account  of  the  anatomy  of  the 
Monostomidae  in  his  description  of  Cyclocoelum  (Monostomum)  mutabile 
(Zeder),  speaks  of  the  mouth  as  a  transverse  oral  opening  leading  to  a 
funnel  shaped  canal  which  narrows  gradually  posteriorly  and  terminates 
in  the  so-called  pharynx.  No  trace  of  a  sucking  organ  was  observed  by 
this  author. 

Following  this  Van  Beneden  (1858)  referred  to  the  above  work  fre- 
quently but  stated  that  the  monostomes  have  only  a  mouth  sucker  situated 
in  the  anterior  region.  In  another  paragraph  of  the  same  work  he  speaks 
of  the  digestive  system  of  Trematodes  as  showing  generally  an  anterior 
sucker  in  the  bottom  of  which  is  situated  the  mouth.  This  he  says  opens 
into  a  second  enlargement  similar  to  the  preceding  sucker,  the  pharyngeal 
bulb.  In  his  figures  of  Cyclocoelum  (Monostomum)  mutabile  (Zeder)  the 
structure  termed  pharyngeal  bulb  above  is  indexed  as  buccal  bulb.  These 
show  the  pharyngeal  bulb  with  no  anterior  sucking  musculature  surround- 
ing the  mouth  opening.  In  a  later  paper  (1861)  the  same  author  describing 
again  this  same  species  spoke  of  the  bulb  and  the  region  preceding  it  which 


22  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [240 

he  said  is  seen  with  difficulty.  A  little  later  in  this  work  in  the  description 
of  Notocotyle  (Monostomum)  verruca  sum  he  employed  the  term  "la  ven- 
tuose  anterieure  ou  plutot  le  buccal,"  applying  it  to  the  spherical  muscular 
bulb  at  the  extreme  anterior  of  this  worm  a  Notocotylid,  evidently  mistak- 
ing this  structure  for  the  same  structure  termed  the  pharyngeal  bulb  in 
the  earlier  work.  His  descriptions  show  clearly  that  the  same  organ  which 
in  the  distomes  is  termed  pharynx  is  here  termed  anterior  sucker  or  buccal 
bulb. 

Some  years  later  Monticelli  (1892)  described  the  mouth  as  small  in 
Monostomum  mutabile  and  Monostomum  expansum;  of  greater  or  less  size 
in  Ogmogaster  plicatum  and  Monostomum  galeatum;  circular  in  Monostomum 
hippocrepis  and  Monostomum  trigonocephalum;  ellipsoidal  in  Monostomum 
cymbium  and  Monostomum  ornatum.  It  is  usually  ventral  and  generally 
situated  in  the  extreme  anterior  end.  When  present  a  prepharynx  of 
variable  length  is  situated  directly  in  front  of  the  pharyngeal  sucker,  the 
"anterior  sucker  or  buccal  bulb"  of  Van  Beneden.  Monticelli  thus  dis- 
tinguishes between  the  funnel  shaped  tapering  canal  of  von  Siebold  (1835) 
and  the  adjoining  posterior  structure;  and  designates  it  as  a  prepharynx. 
He  says  that  in  Notocotyle  and  some  other  genera  of  this  family  the 
prepharynx  is  wanting  and  that  then  the  pharynx  is  anterior  and  plays  the 
r61e  of  an  anterior  sucker.  For  this  reason  he  designates  this  structure  in 
these  genera  as  a  sucker  pharynx. 

Braun  one  year  later,  refers  to  the  description  of  Monticelli  and  sug- 
gests that  a  sucking  organ  has  been  developed  out  of  the  pharynx.  In 
1901  the  same  author  refers  to  the  "bulbus  buccalis"  of  Van  Beneden,  or 
pharynx  of  Monticelli,  as  a  Mundsaugnapf  which  he  says  is  followed  by 
the  esophagus.  In  another  paragraph  of  the  same  work  when  describing 
Monostomum  trigonocephalum  Rud.  (since  removed  to  the  genus  Prono- 
cephalus  by  Looss)  collected  from  the  intestine  of  the  sea  turtle  he  says 
that  the  sucker  is  0.12  mm  long  and  0.09  mm  broad  and  again  states 
that  it  is  followed  by  a  straight  esophagus  0.3  mm  long,  without  a  phar- 
ynx. Thus  Braun  has  construed  the  muscular  structure  at  the  extreme 
anterior  in  the  Notocotylidae,  Pronocephalidae  and  other  families  of  this 
group  to  be  a  development  of  a  structure  similar  to  that  termed  pharynx 
by  Monticelli  in  the  Cyclocoelidae. 

Barker  and  Laughlin  (1911)  accept  this  view  without  comment  and 
describe  the  worms  Notocotyle  quinqueserialis  as  clinging  to  the  intestine 
of  the  muskrat  tenaciously  with  the  well  developed  oral  sucker.  They 
found  no  evidence  of  a  pharynx. 

Taschenberg  (1879)  describes  the  mouth  in  the  genus  Didymozoon 
as  an  opening  followed  by  a  funnel  shaped  duct  leading  to  the  pharynx. 
This  he  states  to  be  generally  characteristic  of  the  entire  group.  Lonnberg 
(1891)  found  in  Didymozoon  lampridis  the  well  developed  sucker  (pharynx  of 


241]  NORTH  AMERICAN  MONOSTOMES  23 

Taschenberg)  and  just  posterior  to  it  a  very  small  muscular  bulb  the  phar- 
ynx. Odhner  (1907)  finds  in  Didymozoon  scombri  Tschbg.  a  similar  pharyn- 
geal  bulb  which  he  figures  and  proves  beyond  doubt  that  the  pharynx  of 
Taschenberg  is  a  very  strongly  developed  sucker  followed  by  an  extremely 
small  pharynx.  In  this  same  notable  work  he  says  that  in  Cyclocoelum 
(Monostomum)  mutabile  (Zeder)  and  other  parasites  where  only  a  pharynx 
is  present  that  there  is  always  a  region  anterior  to  it  which  he  terms  the 
"Mundrohr"  or  "Mundhohle"  (prepharynx  of  Monticelli),  a  structure 
which  by  the  contraction  of  the  inner  walls  changes  the  pharynx  into  a 
sucker.  This  same  region  is  shown  in  the  figures  of  Odhner  for  Didymo- 
zoon scombri  Tschbg. 

Looss  (1899)  speaks  of  the  mouth  sucker  but  gives  no  equivalent  for 
the  pharynx  of  Monticelli.  Later,  however,  he  interprets  the  swelling  at 
the  beginning  of  the  esophagus  in  Microscapha  reticularis  as  a  pharynx. 
Cohn  (1904)  calls  this  to  account  when  he  states  that  this  swelling  is 
nothing  more  than  the  esophageal  sphincter  which  is  present  in  many 
species.  The  same  author  interprets  the  oral  sucker  of  Looss,  or  buccal 
bulb  (anterior  sucker)  of  Van  Beneden,  as  a  pharynx  and  adds  that  it  is 
his  opinion  that  soon  monostomes  will  be  found  with  a  well  formed  sucker 
adjoining  a  typical  pharynx.  The  evidence  given  in  support  of  this  con- 
sists of  the  statement  that  Haplorchis  cahirinus  Looss  has  a  strongly  devel- 
oped pharynx  preceded  by  a  rudimentary  sucker  and  that  he  has  observed 
in  Cyclocoelum  (Monostomum)  mutabile  (Zeder)  and  in  one  other  species 
(to  be  published  later)  a  rudimentary  sucker.  On  the  contrary  Looss 
(1899)  figures  Haplorchis  cahirinus  with  a  well  developed  but  small  oral 
sucker  followed  by  a  somewhat  smaller  but  perfectly  developed  pharynx 
and  in  his  description  of  this  species  states  specifically  that  the  oral  sucker 
and  the  pharynx  are  well  developed  structures.  He  regards  the  rudimentary 
structure  occurring  on  the  ventral  side  as  an  acetabulum.  He  adds  also 
that  the  nerve  commissure  which  according  to  Braun  lies  in  all  the  Digenea 
more  or  less  bent  around  the  dorsal  side  of  the  oral  acetabulum  and  the 
pharynx,  is  in  front  of  the  muscular  sucking  organ  in  the  Monostomidae 
and  therefore  that  organ  is  a  true  pharynx,  tho  this  organ  serves  both  as  a 
sucker  and  a  pharynx. 

Stossich  (1902)  calls  the  pharynx  of  Monticelli  an  "inner  sucker"  which 
he  says  serves  the  same  function  as  the  mouth  sucker  of  other  trematodes. 
Odhner  (1907)  states  that  those  that  acquire  holdfast  organs  in  the 
least  degree  are  the  parasites  of  the  respiratory  organs;  the  group  contain- 
ing Cyclocoelum  mutabile  being  entirely  suckerless.  Kossack  following  the 
decision  of  Monticelli  says  that  the  question  can  be  determined  only  by 
a  study  of  the  position  and  distribution  of  the  nerve  ganglia.  Conse- 
quently he  termed  the  anterior  muscular  structure  a  true  pharynx.  Ward 
(1918)  calls  the  same  structure  the  oral  sucker  and  says  that  no  pharynx  is 


24  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [242 

present.  The  interpretation  of  Braun,  Looss,  Ward  and  others  is  indeed 
well  exemplified  in  many  cases  where  the  anterior  region  is  telescoped 
posteriad  over  the  opened  anterior  portion  of  the  pharynx  (Fig.  46). 

Records  of  an  oral  sucker  in  this  group  are  few,  aside  from  that 
found  in  Cyclocoelum  mutabile  by  Cohn  (1902).  Wedl  (1857)  gives  an  ac- 
count of  the  oral  sucker  in  Monostomum  lanceolatum  as  follows: — "Der 
kleine  Mundnapf  liegt  an  der  Bauchseite  des  zugeschmalerten  Vorder- 
theiles  des  Thieres  (Fig.  15a)  und  ist  nach  riickwarts  von  einem  dickfleisch- 
igen  Bulbus  oesophagus  (b)  begrenzt,  *  *  *  ".  These  with  the  account 
of  the  writer  (Harrah  1921)  in  which  the  oral  sucker  was  described 
in  two  species  of  this  genus  constitute  the  evidence  produced  to  demon- 
strate the  presence  of  the  oral  sucker  in  this  group. 

In  the  light  of  the  foregoing  the  question  brought  out  by  a  long  con- 
tinued controversy  remains  unsettled.  Is  the  structure  termed  the  phar- 
ynx by  Monticelli  (1892)  phylogenetically  a  pharynx  or  an  oral  sucker? 
While  Monticelli  attempted  to  prove  by  the  distribution  of  the  anterior 
nerves  that  the  muscular  bulb,  or  pharynx  as  he  termed  it,  was  a  true 
pharynx,  this  has  not  been  generally  accepted  and  hence  remains  a  matter 
of  much  controversy.  In  the  opinion  of  the  writer  the  brain  commissure 
which  lies  distinctly  anterior  to  the  pharynx  (Fig.  8)  can  be  used  as  a  land 
mark  only  and  in  a  different  state  of  contraction  might  have  its  relative 
position  changed.  The  innervation  is  no  doubt  distributed  to  the  other 
anterior  structures  as  well.  Although  the  nerve  commissure  has  the 
same  relative  position  in  the  distomes  this  alone  does  not  prove  the  phy- 
logenetic  origin  of  the  pharynx,  and  when  a  muscular  sucking  apparatus 
is  found  and  proof  established  of  such  an  organ  anterior  to  and  adjoining 
the  pharynx,  as  predicted  by  Cohn  (1904),  then  and  only  then  can  these 
organs  be  safely  designated  as  oral  sucker  and  pharynx. 

In  this  study  the  writer  has  examined  more  than  one  hundred  speci- 
mens of  the  genus  Cyclocoelum  Brandes  comprising  at  least  fifteen  different 
species.  In  this  material  different  conditions  are  found.  In  Cyclocoelum 
obliquum  Harrah  1921,  Cyclocoelum  halli  nov.  spec.  Cyclocoelum  obscurum 
(Leidy),  Cyclocoelum  triangularum  nov.  spec,  a  very  weak  and  scarcely 
distinct  oral  sucker  is  present.  The  concentration  of  tissue  is  scarcely 
discernible  except  under  the  best  optical  conditions  and  even  in  sections 
there  appears  only  a  concentration  of  tissue  at  this  point  (Figs.  36-42). 
The  outer  circular  band  or  sheath  is  found  to  be  very  light  and  not  a  con- 
tinuous band  as  in  Cyclocoelum  elongatum.  The  above  condition  has 
been  found  to  obtain  in  Cyclocoelum  problemalicum  Stoss.  and  Cyclocoelum 
tringae  (Brandes).  In  these  species  the  sucker  musculature  is  easily  over- 
looked and  when  not  taken  into  account  the  mouth  opening  agrees  well 
with  the  structure  so  clearly  described  by  von  Siebold  (1835)  and  van  Bene- 
den  (1858)  and  that  named  prepharynx  by  Monticelli  (1892).  On  the 


243]  NORTH  AMERICAN  MONOSTOMES  25 

other  hand  in  Cyclocoelum  pseudomicrostomum  an  intermediate  condition 
is  found.  On  first  observation  the  mouth  opening  appears  like  the  one 
just  described;  however,  on  more  careful  scrutiny  a  light  but  well  formed 
sucker  is  discernible.  In  this  case,  however,  the  longitudinal  and  oblique 
muscles  are  actually  increased  immediately  surrounding  the  buccal  duct 
which  leads  inward  toward  the  very  muscular  pharynx  (Fig.  43).  From 
this  more  or  less  muscular  wall,  radial  muscles  extend  outward  having  their 
origin  in  a  weak  band  of  circular  muscles.  This  outside  covering  of  the 
sucker  is  held  in  place  by  the  same  sort  of  transverse  muscles  as  in  the 
distomes.  Were  this  the  only  case  found  one  could  perhaps  accept  Cohn 
(1902:715)  who  has  observed  what  he  terms  a  rudimentary  mouth  sucker 
in  Cyclocoelum  mutabile  (Zeder). 

The  maximum  condition  observed  by  the  writer  was  that  found  in 
Cyclocoelum  elongatum,  in  which  posterior  to  the  opening  of  the  mouth, 
which  is  downward  as  before,  is  seen  a  large  weak  oral  sucker  scarcely  vis- 
ible in  toto  preparations.  It  is  from  one-third  to  one-half  larger  than  the 
pharynx  posterior  to  it  and  extends  from  the  extreme  anterior  of  the 
animal  to  well  over  the  anterior  portion  of  the  pharynx.  It  measures 
314/z  in  length  by  463/x  in  width.  The  musculature  is  much  less  strongly 
developed  than  that  of  the  pharynx  and  consists  of  an  outer  circular  layer 
connected  by  radial,  longitudinal,  and  oblique  muscles  to  a  much  heavier 
inner  circular  band  which  forms  the  muscular  walls  of  the  mouth  (Figs. 
44,  45,  47,  48).  This  muscular  body  is  suspended  by  much  lighter  strands 
of  transverse  muscle  having  their  origin  in  the  musculature  of  the  body 
wall  and  their  insertion  at  times  in  the  outer  circular  band  of  muscles 
covering  the  sucking  musculature  and  again  in  the  radial  muscles  of  the 
sucker  itself.  In  general  the  position  of  this  sucker  is  such  that  it  opens 
downward  but  suspended  as  it  is  a  slight  contraction  of  the  dorsal  sus- 
pensory muscles  and  at  the  same  time  a  relaxation  of  the  ventral  ones 
could  easily  give  to  the  sucker  a  different  position  so  that  its  aspect  would 
be  changed  from  that  of  its  true  antero-ventral  one  (Fig.  29). 

In  all  specimens  studied  the  writer  has  found  evidence  of  the  oral 
sucking  mechanism  and  believes  it  to  be  a  universal  character  in  this 
family.  In  a  study  of  Haematotrephus  similis  Stossich  a  sucker  almost 
as  heavy  as  that  of  Cyclocoelum  elongatum  was  found  (Fig.  28),  and  in  the 
former  species  the  sucker  is  considerably  more  prominent  than  in  Cyclo- 
coelum pseudomicrostomum  and  Cyclocoelum  mutabile.  Cyclocoelum  micro- 
stomum  could  not  be  obtained  for  study  of  this  feature. 

Following  the  oral  sucker  is  a  thin  walled,  lightly  muscular  tube  extend- 
ing posteriad  and  ventrad  to  the  pharynx  and  opening  into  it  on  the 
ventral  side.  The  writer  believes  this  to  be  a  condition  due  to  the  state  of 
contraction  at  the  time  of  preservation  and  that  in  a  fully  extended  speci- 
men the  oral  opening  would  enter  the  pharynx  from  the  anterior  face, 


26  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [244 

thus  leaving  some  150  to  200 ju  between  the  oral  sucker  and  the  pharynx. 
This  portion  is  termed  the  prepharynx  (Fig.  29). 

As  will  be  seen  by  the  description  which  is  to  follow  later  the  structure 
of  the  pharynx  is  practically  identical  in  many  of  the  species  of  this  and 
other  families  and  therefore  must  necessarily  have  developed  from  a 
similar  tissue  in  a  similar  manner.  This  being  the  case  there  remains  the 
functional  differentiation  which  may  come  about  in  the  absence  of  a  well 
developed  oral  sucking  structure.  No  doubt  the  pharynx  aids  the  weak 
sucker  in  drawing  in  food  and  it  is  highly  probable  that  the  suction  pro- 
duced by  these  heavy  muscular  walls  is  indeed  very  great.  As  was  stated 
earlier  in  this  discussion  the  position  of  the  oral  sucking  apparatus  relative 
to  the  pharynx  in  all  those  species  which  do  not  possess  a  strong  oral 
sucking  apparatus  strongly  indicates  this  view. 

As  was  stated  before  the  muscular  bulb,  or  pharynx  of  Monticelli,  is 
identical  in  structure  and  has  no  doubt  arisen  in  the  same  manner  in  all  the 
species  of  this  family.  Even  though  it  may  function  as  a  sucking  organ  in 
some  instances  this  structure  has  not  been  modified  and  does  not  appear 
to  be  typical  sucker  tissue  as  it  has  been  described  in  other  trematodes. 
If,  however,  this  muscular  organ  is  present  in  one  or  more  species  of  this 
genus  at  the  same  time  with  a  distinct  anterior  musculature  which  is 
typical  of  that  tissue  as  found  in  other  groups  of  trematodes  and  is  con- 
stant in  these  species,  then  one  is  justified  in  designating  the  anterior 
musculature  a  sucking  organ  or  oral  sucker  and  the  musculature  posterior 
to  it  a  pharynx  as  it  was  termed  by  Monticelli  (1892). 

Immediately  posterior  and  dorsal  to  the  prepharynx  is  a  muscular 
structure  developed  around  the  wall  of  the  posterior  prepharynx  or  an- 
terior esophagus.  On  first  observation  the  pharynx  appears  as  two  bean- 
shaped  halves  lying  one  on  either  side  of  the  anterior  portion  of  the 
esophagus.  On  more  careful  study,  however,  it  is  found  to  consist  of  heavy 
muscular  halves  bound  together  on  the  edges  by  smaller  bands  of  fibers 
so  that  in  the  true  cross  section  it  appears  as  a  cylinder  with  an  elongated 
dorso-ventral  slit  passing  through  it. 

The  pharynx  is  variable  in  size  and  form  within  the  species  as  well  as  in 
different  species,  and  may  be  in  some  species  distinctly  elongated  while 
in  others  it  is  noticeably  expanded  laterally  and  still  in  others  it  is  spherical. 
It  measures  in  Cyclocoelum  pseudomicrostomum  778/i  and  is  slightly  longer 
than  broad.  In  Cyclocoelum  obscurum  it  is  in  general  spherical  and  meas- 
ures 215  to  298 fj,.  In  Cyclocoelum  macrorchis  it  is  distinctly  longer  than 
broad  and  measures  264  to  314ju  in  length  by  198  to  248/x  in  width.  In 
Cyclocoelum  elongalum  the  pharynx  is  oblong  measuring  264  to  331  fj.  in 
length  by  215  to  281  ju  in  width.  While  the  range  of  measurements  gives 
a  general  idea  of  the  size  and  shape  of  the  pharynx  this  study  has  shown 


245]  NORTH  AMERICAN  MONOSTOMES  27 

that  thfi  individual  which  has  the  longest  pharynx  is  not  always  the  one 
which  has  the  narrowest  one  and  vice  versa. 

As  stated  above  the  size  and  form  of  the  pharynx  is  not  constant  as 
might  be  indicated  by  an  average  or  range  of  measurements.  Cyclocoelum 
obscurum  shows  eight  instances  in  which  the  pharynx  is  round,  two  with  a 
greater  width  than  length,  one  with  a  greater  length  than  width;  this  gives 
an  average  for  eleven  specimens  of  230/i  in  length  and  231  ju  in  width, 
agreeing  closely  with  the  record  that  eight  of  the  eleven  cases  cited  show 
the  pharynx  to  be  spherical.  From  the  range  one  would  infer  from  the 
maximums  that  the  pharynx  is  spherical  but  from  the  minimums  of  less 
transverse  diameter  than  longitudinal.  In  Cyclocoelum  macr orchis  and 
Cyclocoelum  elongatum  every  specimen  measured  shows  for  the  pharynx 
a  greater  length  than  width  while  in  Cyclocoelum  pseudomicrostomum  and 
Cyclocoelum  obscurum  some  were  spherical  while  the  majority  have  a 
greater  length  than  width.  From  this  comparison  one  can  see  readily  that 
the  pharynx  possesses  such  variability  in  size  and  form  in  this  genus  that 
it  can  be  termed  at  best  only  spheroidal. 

The  musculature  of  the  pharynx  is,  as  stated  previously,  similar  in 
all  the  species  of  this  genus  and  consists  of  numerous  fibers  bound  into  bun- 
dles that  are  so  interlaced  as  to  make  a  very  powerful  organ  and  in  the 
absence  of  the  strong  oral  sucker  it  is  quite  probable  that  it  serves  as  a 
sucking  organ  as  was  stated  earlier  in  this  work. 

The  musculature  is  quite  characteristic  of  this  organ  as  it  has  been 
described  in  other  trematodes  and  consists  of  circular,  radial  and  longi- 
tudinal fibers.  The  circular  muscles  are  most  numerous  and  constitute 
approximately  75  percent  of  the  entire  structure.  They  are  pierced  by 
bundles  of  radial  muscles  which  have  their  origin  in  the  outer  layer  of 
circular  muscles  and  their  insertion  in  the  inner  layer  of  the  same  muscles 
whose  fibers  intertwine  all  the  muscles  of  the  circular  and  radial  type,  par- 
ticularly at  their  origin  and  insertion. 

In  most  cases  this  muscular  bulb  stands  with  the  anterior  end  open 
thus  forming  a  continuation  of  the  funnel  shaped  mouth  opening  to  the 
posterior  end  of  the  pharynx  which  in  all  instances  observed  by  the  writer 
is  closed  just  anterior  to  the  esophagus  that  leads  caudad  from  this  organ. 

The  esophagus  is  a  thin  walled  tube  of  varied  length.  In  Cyclocoelum 
elongatum  it  measures  347  to  463 /z;  in  Cyclocoelum  obscurum  331  to  662 /j; 
in  Cyclocoelum.  halli  483 /x  on  the  average.  The  wide  range  of  variation  in 
length  is  due  to  the  fact  that  the  esophagus  takes  an  S-shape  (Fig.  29) 
which  is  no  doubt  due  to  a  state  of  partial  contraction  taken  at  fixation. 
This  condition  makes  it  impossible  to  secure  the  exact  length  of  this  organ. 
Because  of  the  different  states  of  contraction  the  esophagus  is  more  sinuous 
in  some  specimens  than  in  others  and  consequently  shows  a  much  greater 
variation  in  length.  In  view  of  this  fact  the  writer  can  place  very  little 


28  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [246 

weight  on  the  exact  length  of  the  esophagus  as  a  specific  characteristic. 
In  fact  in  some  cases  where  the  toto  specimen  showed  the  esophagus  to  be 
very  short,  sections  of  the  same  specimen  gave  evidence  of  a  relatively 
long  but  much  folded  tube  due  no  doubt  to  contraction. 

In  the  case  of  Cyclocoelum  obscurum  stated  above  the  length  varies 
from  298  to  662/i  making  an  average  for  the  eleven  specimens  of  419/*. 
Under  the  conditions  mentioned  the  average  does  not  represent  the  actual 
length  of  the  esophagus.  It  was  noted  from  a  study  of  this  collection  that 
the  esophagus  of  one  individual  was  more  than  twice  as  long  as  that  of 
another.  However,  the  maximum  length  of  the  esophagus  is  not  repre- 
sented by  the  maximum  measurements  secured  since  in  no  case  has  the 
writer  observed  the  esophagus  when  it  could  be  said  to  form  a  straight 
'line  from  the  oral  sucker  to  the  pharynx.  The  normal  condition  is  repre- 
sented in  figure  29  where  the  esophagus  arises  at  the  dorsal  portion  of  the 
pharynx  and  from  there  takes  a  winding  course  both  laterally  and  dorso- 
ventrally  to  the  intestinal  bifurcation  into  which  it  empties  directly  from 
the  ventral  side  of  the  latter  organ.  The  esophagus  bifurcates  at  the 
posterior  portion  of  the  first  body  sixth  to  form  the  intestinal  crura.  One 
branch  passing  to  the  right,  the  other  to  the  left  side  of  the  body,  thus 
forming  an  arch  which  lies  in  the  anterior  one-sixth  of  the  body.  The 
crura  extend  from  this  parallel  to  the  body  wall,  being  separated  from  it 
only  by  the  vitellaria,  to  the  extreme  posterior  end  where  they  anastomose 
forming  a  posterior  arch.  This  is  separated  from  the  posterior  body  wall 
by  the  excretory  bladder.  The  crura  are  usually  large  with  a  large  lumen. 
However,  in  some  cases  they  are  extremely  irregular  and  show  in  a  few 
instances  more  or  less  distinct  pouches  which  in  some  individuals  appear 
as  distinct  diverticula  and  in  fact  are  as  strongly  exemplified  as  some  of 
those  shown  by  Stossich  (1902)  and  Kossack  (1911)  for  the  genus  Typhlo- 
coelum.  This  feature,  however,  is  not  constant  for  any  species  of  the  genus 
Cyclocoelum  observed  by  the  writer  and  is  probably  due  to  the  pressure 
produced  by  expanded  uterine  loops  which  fill  out  the  space  between  the 
crura  and  in  many  instances  reach  over  the  crura.  Anterior  to  the  intes- 
tinal bifurcation  in  Cyclocoelum  macrorchis  and  Cyclocoelum  obscurum 
there  is  an  evagination  which  makes  a  pronounced  undivided  neck  to  the 
crura  into  which  the  esophagus  opens.  This  appears  in  every  specimen  of 
the  fifty-six  in  the  two  collections.  This  condition  is  in  decided  contrast  to 
the  other  species  studied.  In  these  specimens,  however,  the  intestinal 
crura  are  comparatively  empty  and  show  a  generally  relaxed  condition 
whereas  in  most  of  the  other  specimens  the  crura  are  well  filled  and  appar- 
ently well  extended.  It  is  probable  in  view  of  the  relaxed  and  empty 
condition  of  the  crura  of  the  former  species  that  the  neck  of  the  bifurcation 
is  the  result  of  the  condition  rather  than  a  constant  character  for  the 
species. 


247]  NORTH  AMERICAN  MONOS TOMES  29 

The  excretory  system  of  these  worms  cannot  be  fully  made  out  in 
preserved  material  and  at  most  one  can  obtain  accurate  knowledge  of  only 
a  small  part  of  this  system  without  having  had  opportunity  to  study 
developmental  forms  while  living.  In  general  the  excretory  bladder  can 
be  made  out  in  all  species  as  a  simple  flattened  sac,  except  in  Cyclocoelum 
elongatum,  lying  between  the  posterior  arch  of  the  intestine  and  the  body 
wall,  usually  closely  approached  on  either  side  by  the  posterior  extremities 
of  the  vitellaria.  It  opens  to  the  exterior  on  the  median  dorsal  surface  by 
a  small  duct  surrounded  at  its  exterior  opening  by  a  strong  sphincter. 
Two  main  branches  of  the  system  open  into  the  excretory  bladder  one  on 
either  side.  These  branches  follow  in  general  the  course  of  the  intestinal 
crura  and  are  joined  by  many  secondary  branches  which  anastomose 
freely  forming  a  vast  net-work  ramifying  the  entire  body.  The  ducts  of 
the  system  are  composed  of  relatively  heavy  muscular  walls  which  aid 
in  the  movement  of  the  excretory  products  toward  the  bladder. 

The  nervous  system  so  far  as  has  been  made  out  from  the  material  at 
hand  does  not  differ  materially  from  the  description  of  Lang  (1880).  The 
cephalic  ganglia  are  situated  one  on  either  side  of  the  pharynx  and  are 
connected  by  a  dorsal  commissure  which  spans  the  anterior  alimentary 
organs  between  the  pharynx  and  the  sucker.  In  the  miracidia  are  seen  the 
beehive-shaped  eye-spots  first  observed  by  Van  Beneden  (1861)  and  later 
described  by  Faust  (1918). 

The  vitelline  glands  in  this  family  are  very  much  alike  in  all  genera 
being  composed  of  two  main  canals  which  lie  parallel  to  and  usually  outside 
of  the  intestinal  crura.  From  these  main  stems  side  branches  go  out  both 
dorsally  and  ventrally.  The  glands  are  made  up  of  small  follicular  bodies 
arranged  around  the  ducts  so  as  to  form  grape-like  clusters.  The  develop- 
ment of  these  glands  is  constant  within  a  species  and  may  be  built  up  on 
the  main  stem  with  relatively  few  branches.  The  strongest  development 
of  the  secondary  branches  is  found  in  Cyclocoelum  microstomum  and  Cyclo- 
coelum pseudomicrostomum  and  in  the  genus  Hyptiasmus  where  the 
branches  of  the  vitelline  glands  form  a  net-work  closely  applied  to  the 
intestinal  crura.  The  vitelline  substance  is  conveyed  to  the  ootype  by  a 
duct  from  each  side  in  the  region  of  the  ovarian  complex;  these  pass  to  a 
point  posterior  to  the  shell  gland  where  they  unite.  At  the  point  of  union 
is  usually  found  an  enlargement,  the  vitelline  reservoir.  The  duct  then 
passes  to  the  dorsal  side  of  the  shell  gland  where  it  becomes  embedded  in 
the  latter  organ;  however,  it  emerges  from  this  to  re-enter  it  on  the  anterior 
dorsal  surface  and  just  after  its  entry  joins  the  oviduct  at  the  point  of  its 
enlargement  to  form  the  ootype. 

The  cirrus  pouch  as  stated  by  Kossack  (1911)  shows  little  variation, 
It  is  a  clubshaped  muscular  pouch  containing  a  relatively  large  vesicula 
seminalis  to  which  unites  a  short  weakly  developed  pars  prostatica.  This 


30  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [248 

gives  rise  to  a  relatively  large  cylindrical  unarmed  ductus  ejaculatorius. 
In  most  individuals  the  ductus  ejaculatorius  and  pars  prostatica  are  much 
coiled  inside  the  cirrus  sac  and  can  be  made  out  only  with  considerable 
difficulty.  The  writer  has  had  the  good  fortune  to  have  for  study  two 
specimens  of  Cyclocoelum  brazilianum  Stoss.  one  of  which  has  the  ductus 
ejaculatorius  protruded  from  the  body.  The  other  one  with  the  ductus 
ejaculatorius  extended  into  the  uterus  in  a  case  of  evident  self-copulation. 
(Figs.  31,  35).  In  these  specimens  the  ductus  is  in  excellent  position  for 
study  and  appears  as  described  above.  Through  the  union  of  the  end 
portion  of  the  cirrus  pouch  and  the  uterus  a  relatively  large  genital  atrium 
is  formed. 

The  form  of  the  genital  glands  throughout  the  family  is  in  general  very 
similar.  They  are  usually  round  or  elliptical,  sometimes  flattened  from 
pressure  of  the  surrounding  parts,  with  the  exception  of  Cyclocoelum  mcar- 
ium  (Arned.)  and  in  the  genus  Typhlocoelum  in  which  species  the  testes 
are  lobed.  The  genital  glands  of  the  genus  Cyclocoelum,  the  only  Amer- 
ican genus  thus  far  known  belonging  to  this  family,  are  spherical  in  form. 
The  testes  are  located  so  the  posterior  is  in  or  near  the  posterior  intes- 
tinal arch  and  the  anterior,  a  greater  or  less  distance  from  this,  separated 
often  by  uterus  loops.  Exceptions  to  this  are  found,  however,  in  Cyclo- 
coelum oculobium  (Cohn)  and  Bothriogaster  variolaris  Fuhrmann  in  which 
the  ovary  occupies  the  posterior  intestinal  arch  while  the  testes  are  situ- 
ated in  the  middle  region  of  the  body.  The  vasa  efferentia  given  off  from 
the  testes  unite  a  short  distance  anterior  and  median  to  the  anterior 
testis  in  Cyclocoelum  obscurum,  to  form  the  vas  deferens  which  makes  its 
way  between  the  uterine  loops  to  the  cirrus  pouch  previously  described. 
The  ovary  is  spherical  and  communicates  by  a  short  duct  to  the  compact 
closely  lying  shell  gland. 

The  presence  of  the  receptaculum  seminis  and  Laurer's  canal  have  been 
held  in  question  since  the  earliest  accurate  work  on  the  anatomy  of  these 
worms,  that  of  von  Siebold  (1835)  who  described  in  Monostomum  mutabile 
as  organs  contributing  to  the  formation  of  the  egg  four  distinct  glands,  the 
vitellaria,  which  he  interpreted  as  the  ovary  as  follows: — "Die  Ovarien 
bilden  kurze  blinde  Schlauche,  die  unter  einander  anastomosiren  und  den 
Darmkanal,  nachdem  er  vom  Oesophagus  aus  die  Seitenrander  des  Leibes 
erreicht  hat,  in  seinem  ganzen  weiteren  Verlaufe  wie  ein  Netz  umgeben. 
Es  ist  dies  eine  eigenthumliche  Anordnung,  die  ich  bis  jetzt  noch  bei  keinem 
anderen,  zu  den  Trematoden  gehorigen  Wurme  angetroffen  habe."  The 
three  other  parts  having  to  do  with  the  formation  of  the  shell  are  de- 
scribed by  the  following  characteristic  statements: — "An  der  zweiten 
Abtheilung  der  weiblichen  Geschlechtstheile,  die  zur  Bildung  der  Eier- 
haute  bestimmt  zu  sein  scheint,  lassen  sich  deutlich  drei  eigenthumliche 
Organe  erkennen.  a)  Erstens  fallt  hier  ein  runder,  weissgelber  Korper 


249]  NORTH  AMERICAN  MONOSTOMES  31 

in's  Auge,  der  zur  rechten  Seite  dicht  neben  und  vor  dem  hinteren  Hoden 
liegt,  und  an  Umfang  etwas  kleiner  als  dieser  ist.  b)  Diesem  runden 
Korper  hangt  zweitens  nach  innen  ein  ovaler,  noch  kleinerer  und  ebenfalls 
weissgelb  gefarbter  Korper  an,  der  mit  ersterem  durch  einen  kurzen,  an- 
fangs  weiteren,  nachher  engeren  Kanal  in  Verbindung  steht.  c)  Endlich 
liegt  drittens,  theils  unter  diesen  Organen,  theils  zwischen  dem  runden 
Korper  und  dem  hinteren  Hoden  eine  durchsichtige,  fast  farbelose  und 
unregelmassig  umgranzte,  feinzellige  Masse,  in  die  der  gemeinschaftliche 
kurze  Ovariengang  einmundet,  und  aus  der  der  eierfiihrende  Uterus  her- 
vortritt.  Es  ist  mir  bis  jetzt  nicht  gelungen,  eine  Verbindung  dieses  un- 
regelmassigen  Organes  mit  dem  grtfsseren  runden  Korper  bestimmt  nach- 
zuweisen;  doch  bin  ich  uberzeugt,  dass  eine  solche  wirklich  existirt." 
Van  Beneden  (1861)  in  his  study  of  Monostomum  mutabile  after  character- 
izing the  vitellaria  (vitellogene  Van  Beneden,  Ovarien  von  Siebold)  and 
the  ovary  (germigene  Van  Beneden,  one  of  the  shell  forming  organs  of  von 
Siebold)  says  (p.  74),  that  besides  the  testes  and  the  ovary  only  one  other 
organ  has  been  observed  by  him  in  the  posterior  region  i.e.,  the  vitelline 
duct  which  dilates  to  form  the  vitelline  reservoir.  In  regard  to  the  other 
organs  described  by  von  Siebold  (1835)  he  says  "Sont-ce  la  les  deux  autres 
organes  que  M.  von  Siebold  signale  et  qui  contribuent  a  la  formation  des 
oeufs?  Cela  est  probable!" 

More  recently  Braun  (1892)  stated  that  he  is  able  to  find  the  recep- 
taculum  seminis  only  in  Aploblema,  Cephalogonimus  and  in  the  dis- 
tomes,  and  that  on  the  basis  of  his  own  research  Laurer's  canal  is  wanting 
in  Monostomum  mutabile.  One  year  later  he  states  that  in  the  monostomes 
a  Laurer's  canal  appears  to  be  wanting.  Cohn  (1902)  reported  the  absence 
of  both  these  organs  in  Monostomum  oculobium.  On  the  contrary  Stossich 
in  the  same  year  after  a  thorough  study  of  the  group  confirmed  the  pre- 
sence of  these  organs  in  several  species  belonging  to  at  least  three  genera 
of  this  family.  Arnsdorff  (1908)  describes  for  Monostomum  vicarium  a 
small  receptaculum  seminis.  Kossack  (1911)  after  a  study  of  a  large 
number  of  specimens  belonging  to  different  genera  of  this  family,  viz: 
Cyclocoelum,  Typhlocoelum,  Haematotrephus,  Hyptiasmus,  states  con- 
trary to  the  finding  of  Stossich  that  both  receptaculum  seminis  and  Laurer's 
canal  are  wanting  in  this  family.  S.  J.  Johnston  (1916)  makes  no  mention 
of  either  the  receptaculum  seminis  or  Laurer's  canal  in  any  one  of  the 
three  genera  studied,  Cyclocoelum,  Haematotrephus  and  Hyptiasmus. 

In  a  study  of  a  considerable  number  of  specimens  belonging  to  several 
species  of  the  genus  Cyclocoelum  the  writer  has  observed  the  presence  of 
the  receptaculum  seminis.  In  addition  to  the  observations  made  on  the 
American  material  the  writer  has  been  given  the  opportunity  through  the 
efforts  of  Professor  Henry  B.  Ward  and  the  courtesies  extended  him  by  the 
Curators  of  the  museums  of  Berlin,  Gottingen,  and  Vienna,  to  study  Cyclo- 


32  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [250 

coelum  mutabile,  Cyclocoelum  problematicum,  Cyclocoelum  ovopunctatum, 
Cyclocoelum  brazilianum,  Cyclocoelum  tringae,  and  Haematotrephus  similis. 
In  all  of  these  species  a  small  spherical  receptaculum  seminis  has  been 
found,  in  position  median  and  dorsal  to  the  ovary  (Figs.  20-24,  26  and  27). 

On  the  same  dorsal  level  with  the  receptaculum  semnis  and  posterior 
to  the  latter  and  the  ovary  one  finds  the  compact  shell  gland,  in  size  ap- 
proximately equal  to  the  ovary.  It  is  composed  of  unicellular  glands  closely 
packed  together,  each  of  which  empties  its  secretion  into  the  ootype  by 
means  of  a  short  straight  canal;  these  ducts  form  the  inner  portion  of  the 
gland.  The  ootype  in  the  central  portion  of  this  gland  gives  rise  to  the 
uterus  which  in  turn  expands,  immediately  upon  emerging,  into  a  large 
receptaculum  semnalis  uterinum.  During  the  sexual  activity  of  the  worm 
this  pouch  is  filled  with  spermatozoa.  In  the  genus  Cyclocoelum,  the  uterus 
forms  relatively  short  closely  packed  loops,  in  general  going  out  from  the 
middle  line  of  the  body.  Relatively  few  stretches  go  directly  across  the 
body.  The  uterus  fills  out  the  entire  space  between  the  crura,  then  by  a 
re'atively  straight  stretch  it  spans  the  distance  to  the  genital  atrium  in  the 
region  of  the  pharynx.  In  lateral  extent  the  uterus  reaches  in  general  to 
the  middle  or  outer  wall  of  the  intestine  or  rarely  even  out  to  the  body  wall, 
as  in  Cyclocoelum  halli.  This  species  differs  in  this  respect  from  other 
species  of  the  genus  and  according  to  the  generic  limits  of  Kossack  does  not 
belong  here  if  this  condition  is  a  diagnostic  factor.  Cyclocoelum  halli, 
however,  conforms  so  closely  to  the  genus  in  other  respects  and  does  not 
conform  to  the  genus  Haematotrephus  in  that  the  uterine  loops  do  not 
bend  around  the  genital  organs  so  that  the  writer  feels  justified  in  placing 
it  in  the  genus  Cyclocoelum.  Evidently  there  is  little  justification  for  the 
creation  of  a  new  genus  based  largely  on  the  extent  of  the  uterus  and  hence 
the  limits  of  the  genus  Cyclocoelum  have  been  extended  to  include  this 
species. 

The  condition  known  as  a  situs  inversus  is  a  common  feature  of  this 
family.  Looss  (1899)  asserted  that  in  all  forms  in  which  the  genital  pore 
is  median  there  is  a  possibility  that  sexual  amphitypy  will  occur  and 
suggested  that  in  Monostomes  where  this  is  the  case  situs  inversus  will 
probably  be  found.  Cohn  (1902)  was  the  first  to  record  this  condition 
in  the  group  when  he  found  in  Spaniometra  oculobia  (Cohn)  a  situs  inversus 
of  the  genital  glands  in  a  ratio  of  9:5.  Kossack  (1911)  added  to  this  by  his 
observations  on  Cyclocoelum  problematicum  Stoss.,  Cyclocoelum  ovopunc- 
tatum Stoss.,  and  Cyclocoelum  vicarium  (Arnsd.)  in  which  he  says  that  on 
the  average  the  right  and  left  positions  are  equally  frequently  present. 

The  writer  has  found  a  similar  condition  to  exist  in  all  species  of 
Cyclocoelum  represented  in  North  America  as  well  as  being  able  to  verify 
the  observations  of  Kossack  on  Cyclocoelum  problematicum  and  Cyclocoelum 
ovopunctatum.  Reference  to  the  following  table  shows  that  the  right  and 


251] 


NORTH  AMERICAN  MONOSTOMES 


33 


left  positions  are  on  the  whole  equal  in  number  and  where  significant 
differences  occur  they  are  perhaps  due  to  the  small  number  of  individuals 
studied.  In  Cyclocoelum  obscurum  with  sixty  specimens  in  the  lot  the 
difference  is  relatively  small.  The  total  of  ninety-four  specimens  in  all 
show  an  approximately  equal  count  for  each  arrangement. 


Ante- 
rior 
testis 

Cirrus 
pouch 

Number  of  uterine  loops 
between  testis 

Total  uterine 
loops  on  side  of 
anterior  testis 

Rt. 

Lt. 

Rt. 

Lt. 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

25- 
30 

30- 
35 

35- 
40 

40- 

45 

45- 
50 

C.  obscurum  .  .  . 

34 

26 

28 

32 

1 

1 

5 

4 

6 

3 

1 

9 

23 

22 

5 

2 

C.  elongatum  .  . 

4 

4 

3 

4 

1 

5 

1 

1 

2 

3 

C.  pseudomicro- 
stomum.  .  . 

3 

1 

2 

2 

1 

1 

1 

1 

1 

2 

1 

C.  macrorchis  .  . 

8 

14 

7 

15 

1 

6 

3 

6 

1 

3 

2 

... 

... 

1 

4 

12 

5 

... 

Total  numbers  . 

49 

45 

40 

54 

The  variation  in  the  position  of  the  testes  from  one  another  is  equally 
of  little  importance  from  the  standpoint  of  specific  diagnosis.  However, 
since  Stossich  used  this  as  the  means  of  separation  of  species  in  Cyclocoe- 
lum and  Haematotrephus  the  writer  feels  it  worth  while  to  give  here  the 
result  of  observations  on  American  material.  Kossack  raised  objections 
to  the  importance  assigned  this  point  by  Stossich  and  showed  that  the 
variation  within  a  species  was  even  greater  than  that  between  the  genera 
before  mentioned. 

The  study  of  the  American  material  has  served  to  substantiate  the 
view  of  Kossack  (1911)  reached  by  study  of  the  European  material. 
Reference  to  table  shows  the  number  of  uterine  loops  to  vary  from  none 
where  the  testes  lie  contiguous  to  one  another  to  nine  while  the  entire 
number  of  uterus  loops,  counted  always  on  the  side  of  the  anterior  testis, 
is  likewise  variable  and  appears  to  bear  no  relation  to  the  total  number  of 
uterine  loops  between  the  testes  of  the  individual  since  the  specimen 
which  showed  nine  loops  between  the  testes  has  in  all  only  38  loops  while 
in  another  individual  of  the  same  lot  of  Cyclocoelum  obscurum,  which  had  a 
total  of  40  loops  only  3  could  be  found  between  the  testes.  Other  examples 
are  8  and  43;  3  and  44;  7  and  39  as  compared  to  1  and  39.  These  are  a  few 
examples  taken  from  Cyclocoelum  obscurum.  Other  species  show  the  same 
to  be  true  except  in  Cyclocoelum  halli  and  Cyclocoelum  triangularum  where 
the  relative  positions  of  the  genital  glands  appear  to  be  constant.  How- 


34  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [252 

ever,  since  the  number  of  specimens  here  is  small  the  writer  is  inclined 
to  attach  relatively  little  importance  to  this  feature. 

The  life  history  of  this  group  is  relatively  unknown,  although  the  ear- 
liest record  of  a  monostome  larva  is  said  to  date  from  1817.  An  early 
account  is  found  in  Filippi  1859.  This  author  obtained  from  Bythinia 
tentaculata  (L)  [—Paludina  impura  of  Filippi]  a  larva  he  named  Cerceria 
lophocerca  which  he  described  (1859:5)  as  follows:  "Elle  est  caracterisee 
par  un  bulbe  pharyngien  assex  fort,  par  la  presence  de  deux  yeux  ou  taches 
pigmentaires  semilunaires  avec  une  petite  lentille  dans  la  concavite,  et 
par  une  queue  munie  d'une  crete  membraneuse  longitudinale.  Dans  1'in- 
te*rieur  du  corps  on  voit  des  rudiments  d'organes  sexuels  sous  la  forme  de 
trois  masses  vesiculaires." 

According  to  Liihe  (1909)  the  determination  of  Filippi  is  doubtful 
since  the  description  and  figures  show  a  close  resemblance  to  Cercaria 
fuhopunctata  Ercol.  which  is  an  undoubted  distome  larva.  Cort  (1915) 
on  the  other  hand  recognized  distinct  features  in  this  larva  and  stated 
that  it  is  "entirely  different  from  all  other  monostomes  known."  As  such 
it  stands  alone  and  unidentified. 

While  the  description  of  Filippi  is  meager  and  bereft  of  many  diagnos- 
tic characters  a  few  outstanding  features  point  to  its  alliance  to  this  group. 
This  relationship  is  shown  by  the  absence  or  at  most  only  poorly  devel- 
oped oral  sucker  (Filippi,  pi.  I,  fig.  3),  by  the  presence  of  a  strongly  devel- 
oped pharynx,  and  by  the  position  of  the  three  "rudimentary"  sex  organs. 

Key  to  species  of  Cyclocoelum 

1  (6)     Uterus  restricted  to  the  intercecal  zone 2 

2(5)     Testes  unequal  in  size 3 

3(4)     Pharynx  larger  than  oral  sucker;  ratio  of  posterior  testis  to 

ovary  2:1 Cyclocoelum  mutabile  (Zed.) 

4(3)     Oral  sucker  and  pharynx  small,  approximately  equal  in  size ; 

ratio  of  anterior  testis  to  ovary  4:3 

Cyclocoelum  cuneatum  nov.  spec. 

5 (2)     Testes  equal  in  size.    Oral  sucker  larger  than  pharynx ;  ratio 

of  testes  too  vary  3:1 Cyclocoelum  leidyi  nov.  spec. 

6(1)     Uterus  not  restricted  to  intercecal  zone 8 

7(26)  Uterus  folding  around  the  crura  both  dorsally  and  ventrally ...  9 

8(21)  Cental  glands  separated  by  uterine  loops 10 

9(16)  Testes  equal  in  size 11 

10(13)  Pharynx  larger  than  sucker;  vitellaria  extending  laterally 

beyond  medial  wall  of  crura 12 

11(12)  Ratio  of  testes  to  ovary  5:2 

Cyclocoelum  pseudomicrostomum  nov.  spec. 

12(11)  Ratio  of  testes  to  ovary  4:3 . . .  Cyclocoelum  microstomum  (Crepl.) 


253]  NORTH  AMERICAN  MONOSTOMES  35 

13(10)  Sucker  larger  than  the  pharynx 15 

14(15)  Vitellaria  strongly  developed,  extending  to  inner  wall  of 

intestine;  ratio  of  testes  to  ovary  2:1 

Cyclocoelum  macrorchis  nov.  spec. 

15(14)  Vitellaria   weakly   developed,   rarely  reaching   middle   of 

crura;  ratio  of  testes  to  ovary  2:1 

Cyclocoelum  mcarium  (Arnsd.) 

16(9)     Testes  unequal  in  size 18 

17(20)  Oral  sucker  twice  as  large  as  pharynx 19 

18(19)  Ratio  of  posterior  testis  to  ovary  2:1 

» Cyclocoelum  obscurum  (Leidy) 

19(18)  Ratio  of  posterior  testis  to  overy  3:1 

Cyclocoelum  owpunctatum  Stoss. 

20(17)  Oral  sucker  not  twice  the  size  of  pharynx.      Ratio  of  poste- 
rior testis  to  ovary  3:1 Cyclocoelum  problematicum  Stoss. 

21(8)     Genital  glands  contiguous,  not  separated  by  uterine  loops. .  .24 
22(25)  Testes  unequal  in  size;  oral  sucker  twice  as  large  as  pharynx 25 

Cyclocoelum  wilsoni  nov.  spec. 

24(23)  Ratio  of  posterior  testis  to  ovary  2:1 

Cyclocoelum  tringae  (Brandes) 

25(22)  Testes  equal  in  size;  oral  sucker  and  pharynx  approximately 

equal.    Ratio  of  testes  to  ovary  10:7 

Cyclocoelum  triangularum  nov.  spec. 

26(7)  Uterus  passing  dorsally  over  intestinal  crura  and  vitellaria 
to  body  wall;  vitellaria  moderately  developed,  rarely  ex- 
tending beyond  middle  of  crura 30 

27(28)  Sucker  1^  times  pharynx;  testes  unequal;  ratio  posterior 

testis  to  ovary  3 :2 Cyclocoelum  brazilianum  Stoss. 

28(29)  Sucker  and  pharynx  equal  in  size;  testes  equal;  ratio  of 

testes  to  ovary  2:1 Cyclocoelum  halli  nov.  spec. 

Description  of  species 

CYCLOCOELUM  LEIDYI  nov.  spec. 

[Figures  1,  2,  33] 
Syn:  Monostomum  mutabile  Leidy  1885,  nee  Zeder  1800 

This  collection  contains  five  specimens  described  by  Leidy  (1885)  as 
follows:  "From  the  thoracic  cavity  of  a  Gray  Snipe,  Gallinago  wilsoni, 
Dr.  Warren  (of  Westchester)  obtained  five  Flukes,  18mm  long,  by  4mm 
broad.  These  appear  to  be  Monostomum  mutabile." 

These  specimens  are  readily  recognized  as  belonging  to  the  genus 
Cyclocoelum  Brandes  (1892)  but  are  distinctly  different  from  Cyclocoelum 
mutabile  and  represent  a  new  species.  The  following  description  shows  the 
characteristic  differences  between  the  two  species. 


36  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [254 

These  flukes  are  16  to  18  mm  long  by  4  to  4 . 5  mm  broad.  The  margins 
of  the  body  are  practically  parallel  in  the  posterior  two-thirds  of  the  body. 
The  anterior  one-third  tapers  to  a  weakly  rounded  point.  The  subterminal 
mouth  is  surrounded  by  a  weakly  developed  sucking  musculature  which 
is  approximately  three  times  the  size  of  the  small  pharynx.  The  small 
ovoid  pharynx  measures  231  ju  broad  by  281  M  long.  The  slender  esophagut 
which  is  curved  in  the  form  of  an  S  measures  33 1//  in  length.  It  opens  inso 
the  middle  of  the  dorsal  side  of  the  intestinal  bifurcation.  The  voluminous 
intestinal  crura  run  parallel  to  the  margins  of  the  body  throughout  their 
entire  course.  The  vitellaria  are  moderately  developed  and  occupy  the 
region  lateral  to  the  crura.  They  extend  laterally  to  the  inner  wall  of  the 
crura  and  fold  both  dorsally  and  ventrally  around  them.  They  extend  an- 
teriorly not  quite  to  the  most  anterior  portion  of  the  intestinal  bifurcation 
and  are  separated  at  the  posterior  end  only  by  the  excretory  bladder.  The 
uterus  fills  the  entire  space  between  the  intestinal  crura.  It  lies  in  the 
mid  dorso-ventral  region,  is  profusely  coiled  and  does  not  extend  out 
beyond  the  inner  wall  of  the  intestine.  Genital  glands  are  confined  to 
the  posterior  intestinal  arch.  The  posterior  testis  is  situated  in  the  middle 
line  of  the  body  and  lies  directly  in  the  arch  formed  by  the  intestine. 
The  anterior  testis  is  a  little  removed  and  is  contiguous  to  the  crura.  They 
are  equal  in  size  and  measure  877  to  910ju  in  diameter.  The  much  smaller 
ovary  lies  on  the  side  of  the  body  opposite  to  the  anterior  testis  and  in  a 
transverse  plane  between  the  two  testes.  It  is  spherical  and  measures  from 
380  to  390/z  in  diameter.  Dorsally  and  on  the  inner  posterior  side  of  the 
ovary  is  a  small  spherical  receptaculum  seminis  82  to  99/x  in  diameter, 
which  joins  by  a  short  duct  the  oviduct  shortly  after  its  emergence  from 
the  ovary.  Laurer's  canal  is  not  present.  As  the  oviduct  passes  poste- 
riorly into  the  adjacent  shell  gland  aggregate  it  is  joined  by  the  vitelline 
duct.  At  this  point  the  oviduct  enlarges  to  form  the  ootype.  Just  after 
the  uterus  emerges  from  the  compact  shell  gland  a  second  enlargement  is 
seen,  the  receptaculum  seminalis  uterinum.  It  extends  posteriorly  to  the 
crura  where  it  doubles  on  itself  and  pursues  its  coiled  winding  course  to  the 
genital  pore  which  is  situated  ventral  to  the  middle  region  of  the  pharynx. 
The  cirrus  pouch  is  182/z  broad  by  331 /x  long  and  reaches  to  the  middle 
of  the  intestinal  crura  at  their  bifurcation.  The  genital  pores  open  sep- 
arately into  a  small  genital  atrium.  Eggs  thick  shelled  ovals,  66  by  117^ 
when  fully  mature.  They  contain  in  the  anterior  portion  of  the  uterus  well 
developed  miracidia  as  evidenced  by  the  dark  eye  spots. 

Habitat:  Thoracic  cavity  Host:  Gallinago  wilsoni 

Locality:  Westchester,  Pa.  Date:  1885 

Collector:  Dr.  H.  W.  Warren  No.  106  Leidy  Collection. 

A  comparison  of  this  material  with  the  data  given  by  Stossich  (1902: 
13)  and  by  Kossack  (1911:510)  for  Cydocoelum  mutabile  (Zeder)  as  well  as 


255]  NORTH  AMERICAN  MONOSTOMES  37 

comparison  with  specimens  of  Cyclocoelum  mutabile  obtained  from  the 
Gottingen  museum  demonstrates  clearly  that  this  is  a  distinct  species. 
It  is  similar  to  Cyclocoelum  mutabile  in  the  size  and  form  of  the  body,  in 
the  lateral  extent  of  the  uterine  loops,  the  extent  and  development  of  the 
vitellaria,  the  size  of  the  ovary,  and  the  size  and  shape  of  the  eggs. 

It  differs  from  this  species  in  having  a  much  smaller  pharynx,  a  much 
larger  sucker,  a  longer  esophagus,  larger  testes,  and  a  relatively  heavier 
and  more  irregularly  folded  uterus.  This  species  is  similar  to  Cyclocoelum 
problematicum  Stossich  in  the  size  of  the  testes  and  the  extent  of  the 
vitellaria  but  differs  from  that  species  in  having  a  smaller  pharynx  and  a 
broader,  thinner  and  less  muscular  body  in  proportion  to  its  length.  For 
comparison  with  this  species  a  figure  (Fig.  3)  of  Cyclocoelum  mutabile 
(Zed.)  is  placed  beside  that  of  Cyclocoelum  leidyi. 

CYCLOCOELUM  PSEUDOMICROSTOMUM  nov.  spec. 
[Figures  4,  27,  30,  43] 

Large  monostomes  13  to  14.5  mm  in  length  by  4  to  4.5  mm  in  greatest 
width  which  is  found  at  the  beginning  of  the  posterior  body  third.  From 
this  point  forward  the  side  walls  taper  gradually  to  the  end  of  the  anterior 
body  third,  at  which  point  they  bend  inwardly  more  sharply  to  form  a  small 
obtusely  rounded  end.  The  posterior  end  is  bluntly  rounded.  The  mouth 
is  subterminal,  surrounded  by  an  external  banding  musculature  which 
measures  662  to  745  ju  in  diameter.  This  is  followed  by  a  large  heavy 
slightly  elongate  pharynx  778  to  910/x  in  length  by  745  to  844/x  in  width. 
The  genital  pore  lies  median  and  ventral  to  the  forward  end  of  the  pharynx. 
From  this  point  the  cirrus  pouch  stretches  posteriad  almost  to  the  posterior 
wall  of  the  intestinal  bifurcation.  The  vitellaria  extend  from  the  posterior 
end  of  the  cirrus  pouch  to  the  excretory  bladder  in  the  posterior  end  of  the 
body.  It  is  even  more  strongly  developed  than  that  of  Cyclocoelum 
microstomum  and  in  its  lateral  extent  passes  the  inner  wall  of  the  crura  and 
over  the  lateral  folds  of  the  uterine  loops  which  in  this  species  rarely  pass 
over  the  inner  wall  of  the  crura.  The  testes  as  in  other  species  of  this  genus 
lie  in  the  posterior  region  of  the  body  and  within  the  intestinal  crura.  The 
posterior  testis  does  not  fill  the  entire  intestinal  arch,  is  antero-posteriorly 
flattened  and  measures  827  to  910/z  in  width  by  993  to  1192//  in  length, 
while  the  anterior  testis  which  is  separated  from  it  by  uterine  loops  meas- 
ures 745  to  993 AC  in  width  by  1076  to  1324/z  in  length.  The  ovary  lies  on 
a  level  with  the  anterior  margin  of  the  posterior  testis  and  adjacent  to  the 
cecum  opposite  to  the  anterior  testis,  is  much  smaller  and  spherical, 
measuring  413  to  496 ju  in  diameter.  Dorsal  to  the  ovary  is  the  spherical 
receptaculum  seminis  148  to  165 ju  in  diameter.  The  shell  gland  is  similar 
in  size  to  the  ovary  and  occupies  a  position  dorsal  and  posterior  to  that 
structure.  As  was  stated  above  the  uterus  does  not  usually  pass  over  the 


38  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [256 

inner  wall  of  the  intestine  and  fills  out  entirely  the  space  between  the 
crura.  The  eggs  are  thick  shelled  ovals,  51  to  66 /*  in  width  by  102 /x  in 
length. 

Habitat:  Lung  Host:  "Wild  duck" 

Locality:  Omaha,  Nebr.  Date:  1903 

Collector:  C.  E.  Stringer  No.  1041  Ward  Collection 

This  species  is  also  found  in  the  Leidy  Collection  vial  no.  186  which  has 
been  dried  out  and  is  in  a  poor  state  of  preservation.  John  C.  Johnson 
collected  this  species  from  Fulica  americana  taken  at  Golden  Gate  Park, 
San  Francisco,  Cal.  in  January  1919. 

Cyclocoelum  pseudomicrostomum  finds  its  nearest  relative  in  Cyclocoe- 
lum  microstomum  (Crepl.).  The  two  species  are  of  nearly  equal  size. 
The  pharynx  of  the  former  is  distinctly  larger,  the  testes  are  not  of  equal 
size  as  in  C.  microstomum  and  are  slightly  broader  than  long  probably  due 
to  pressure  from  the  closely  packed  uterus.  The  ovary  of  Cyclocoelum 
pseudomicrostomum  is  noticeably  smaller  than  that  of  Cyclocoelum  micro- 
stomum, while  the  lateral  extent  of  the  uterus  in  the  former  species  is  more 
restricted.  With  respect  to  the  development  of  the  vitelline  glands 
Cyclocoelum  pseudomicrostomum  presents  the  heaviest  development  found 
in  any  known  species  of  this  genus. 

CYCLOCOELUM  HALLI  nov.  spec. 
[Figures  5,  11,  20,  36-42] 

Large  monostomes  varying  in  length  from  11  to  14  mm  in  width  by  3 
to  4  mm  in  greatest  width  which  is  found  slightly  posterior  to  the  middle 
of  the  body.  From  this  point  the  body  tapers  anteriorly  to  almost  a 
point  and  posteriorly  only  a  little,  forming  an  obtusely  rounded  end. 
The  body  is  muscular,  dorsally  convex,  and  ventrally  flat  or  slightly  con- 
cave. The  body  wall  is  entirely  covered  with  numerous  small  pits  ob- 
served by  Zeder  (1803)  in  Monostoma  mutabile.  The  subterminal  mouth 
leads  by  a  funnel-shaped  tube  to  the  pharynx.  This  tube  or  mouth 
proper  is  surrounded  by  a  concentration  of  musculature  which  on  the 
outer  margin  is  formed  into  circular  bands,  the  outer  covering  of  the  sucker 
(Figs.  36  to  42).  The  sucker  is  spherical  in  form  and  measures  387 /z  in 
diameter.  It  is  separated  from  the  smaller  (263 /z)  but  more  heavily  muscu- 
lar, spherical  pharynx,  by  the  nerve  commissure.  The  esophagus  is  483  ju 
in  length  and  extends  from  the  posterior  portion  of  the  pharynx  to  the 
dorsal  side  of  the  intestinal  bifurcation.  The  latter  a  simple  tubular  struc- 
ture lies  along  the  margins  of  the  body  for  its  entire  length  and  anasto- 
moses at  the  posterior  end.  As  previously  described  the  excretory  system 
is  composed  of  a  system  of  tubules  ramifying  the  entire  body  in  this 
species,  as  in  Cyclocoelum  elongatum.  These  tubules  anastomose  and 
empty  into  the  excretory  bladder.  In  this  species  a  single  thin  walled  sac 


257]  NORTH  AMERICAN  MONOSTOMES  39 

which  opens  to  the  exterior  by  a  small  dorsal  pore.  The  genital  glands  are 
situated  in  the  posterior  fifth  of  the  body  where  they  are  closely  packed  in 
the  posterior  arch  of  the  intestine,  the  posterior  testis  almost  entirely 
filling  this  space.  It  is  slightly  flattened  antero-posteriorly  and  measures 
in  its  greatest  dimension  1052 /i  and  in  an  axis  at  right  angles  to  this,  894 /x. 
The  anterior  testis  situated  a  short  distance  cephalad  to  the  posterior, 
is  spherical  in  shape  and  a  little  smaller,  having  a  diameter  of  894ju.  The 
two  testes  are  separated  by  a  particularly  long  loop  of  the  uterus  which 
extends  to  the  intestinal  arch,  and  in  some  instances  even  beyond,  and 
usually  folds  back  part  way  forming  a  double  loop.  The  vasa  efferentia 
given  off  from  the  anterior  margins  of  the  two  testes  unite  cephalad  and 
mesad  to  the  anterior  testis  to  form  the  vas  deferens  which  takes  a  fairly 
straight  course  to  the  cirrus  pouch  with  which  it  unites. 

The  cirrus  pouch  is  a  rather  large  oblong  sac  extending  from  the 
pharynx  to  a  short  distance  beyond  the  anterior  wall  of  the  intestinal 
bifurcation.  It  opens  into  a  small  genital  atrium  which  in  turn  opens  to 
the  exterior,  ventral  to  the  pharynx. 

The  ovarian  complex  is  situated  opposite  to  and  on  a  level  with  the 
anterior  testis.  The  ovary  is  very  much  smaller  than  the  testes,  measuring 
434/1  in  diameter.  Dorsal  to  this  is  the  receptaculum  seminis,  the  duct 
from  which  joins  the  oviduct  before  it  enters  the  shell  gland.  The  shell 
gland,  a  compact  spherical  organ,  is  situated  dorsal  and  posterior  to  the 
ovary.  It  has  a  diameter  of  388 ju.  The  vitellaria  lie  between  the  lateral 
body  wall  and  the  external  wall  of  the  digestive  crura  over  which  they 
seldom  pass.  They  extend  from  the  posterior  pharyngeal  region  to  the 
extreme  posterior  end  where  they  are  separated  by  the  excretory  bladder. 
The  vitelline  glands  are  made  up  of  small  follicular  grape-like  clusters 
arranged  along  a  main  stem,  which  in  the  region  of  the  anterior  testis 
gives  rise  to  the  vitelline  ducts.  These  pass  mesad  and  unite  a  short 
distance  posterior  to  the  shell  gland  to  form  the  common  duct  which 
passes  straight  to  the  shell  gland.  It  enters  this  at  the  posterior  side 
and  passes  through  the  outer  portion  of  this  organ  to  its  union  with  the 
oviduct  just  after  the  entrance  of  the  latter  into  the  shell  gland.  The 
oviduct  then  enlarges  to  form  the  ootype.  On  emergence  from  the  shell 
gland  the  uterus  enlarges  to  form  a  large  pouch,  the  receptaculum 
seminalis  uterinum.  From  this  the  uterus  makes  a  few  short  loops  and  then 
the  long  loop,  previously  mentioned,  which  separates  the  testes.  From 
this  point  forward  it  lies  in  more  or  less  regular  transverse  folds  which 
extend  out  to  the  vitellaria,  tho  in  some  instances,  particularly  in  the 
posterior  three-fifths  of  the  body,  these  loops  extend  to  the  body  wall. 
In  the  anterior  fifth  of  the  body  the  uterine  loops  are  not  so  long  and 
here  fill  out  entirely  the  space  between  the  intestinal  crura.  From  the 


40  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [258 

bifurcation  of  the  intestine  the  uterus  reaches  in  a  relatively  straight 
stretch  to  the  genital  atrium. 

The  eggs  are  large,  thick  shelled  ovals,  measuring  161  ju  in  length  by  99  /* 
in  breadth.  The  double,  dark  eyespots  give  evidence  of  the  developing 
miracidium  within  the  eggs  before  they  have  passed  in  their  course  anterior 
to  the  middle  region  of  the  body. 

Habitat:  Abdominal  air-sacs.  Locality:  host  taken  in  Raleigh 

Host:  Totanus  melanoleucus  (?)  N.  C. 

Date:  April  7,  1894  Collector:  W.  C.  Hall 

No.  21.90  Ward  collection 

Habitat:  Liver?  or  Lung?  Locality:  Creston,  Iowa 

Host:  Totanus  solitarius  Collector:  W.  C.  Hall 

Date:  Aug.  30,  1895  No.  21 . 763  Ward  collection 

Filed  among  the  records  of  Hall  is  a  statement  that  he  collected  5 
specimens  from  the  air  sacs  of  Totatnus  flampes  Sept.  4,  1895,  which  he 
believed  to  be  this  species.  The  material  from  this  host  has  not  been  found. 
This  species  is  most  closely  related  to  Cyclocoelum  brazilianum  Stossich 
and  resembles  that  form  in  the  lateral  extent  of  the  uterus,  the  relative 
position  of  the  genital  glands,  and  in  the  size  of  the  ovary.  It  differs, 
however,  in  the  size  of  the  testes,  the  more  weakly  developed  vitellaria, 
and  relative  size  of  the  oral  sucker  and  pharynx,  these  being  of  equal  size 
in  C.  halli  while  in  C.  brazilianum  the  sucker  is  distinctly  larger  than  the 
pharynx. 

CYCLOCOELUM  WILSONI  nov.  spec. 
[Figure  6] 

Medium  sized  monostomes  12  mm  long  by  3  mm  wide  in  maximum 
which  is  found  at  the  beginning  of  the  posterior  one-fifth  of  the  body. 
Posterior  and  bluntly  rounded.  Anterior  to  the  point  of  greatest  width 
the  body  tapers  gradually  to  a  blunt  but  relatively  small  point.  The 
mouth  sucker  measures  374/*  in  diameter  and  is  one-third  larger  than 
the  oval  pharynx  which  measures  298/*  in  length  by  269 /*  in  width.  The 
esophagus  is  relatively  long  and  gives  rise  by  bifurcation  to  the  simple 
intestinal  crura,  which  as  in  other  species  run  parallel  to  the  body  wall 
and  anastomose  in  the  posterior  end  of  the  body.  The  genital  aperture 
is  ventral  to  the  middle  of  the  pharynx.  The  cirrus  pouch  extends  from 
this  point  to  the  middle  of  the  intestinal  bifurcation.  The  follicular  yolk 
glands  extend  from  the  anterior  wall  of  the  intestinal  bifurcation  almost 
to  the  excretory  bladder  at  the  posterior  end.  In  lateral  expanse  they  pass 
over  the  external  wall  of  the  intestinal  crura  to  the  middle  of  that  organ 
where  they  meet  the  furthest  expanse  of  the  uterus.  The  uterus  in  this 
species  lies  entirely  anterior  to  the  anterior  testis  and  fills  out  the  space 
between  the  crura,  folding  both  dorsally  and  ventrally  over  the  walls  of 


259]  NORTH  AMERICAN  MONOSTOMES  41 

these  to  the  middle  region  of  the  same.  The  genital  glands  lie  contiguous 
to  one  another  in  the  posterior  arch  of  the  intestine.  The  posterior  testis 
lies  a  little  posterior  to  and  a  little  more  nearly  in  the  middle  of  the  arch 
than  the  anterior  one  which  is  smaller  and  contiguous  to  the  former, 
filling  out  the  opposite  portion  of  the  intestinal  arch.  The  testes  are  not 
separated  by  uterine  loops  as  is  generally  true  in  this  genus.  The  anterior 
testis  is  spherical,  910ju  in  diameter  while  the  posterior  testis  is  slightly 
elongated  and  measures  993 n  in  length  by  910/z  in  width.  The  ovarian 
complex  lies  anterior  to  and  adjacent  to  the  posterior  testis.  The  ovary  and 
shell  gland  are  spherical,  equal  in  size,  and  measure  413  to  447  ^  in  diame- 
ter. The  small  spherical  receptaculum  seminis  lies  partially  embedded  in 
the  shell  gland  and  measures  150/i  in  diameter.  The  eggs  are  thick  shelled 
ovals  and  measure  150/z  in  length  by  76/i  in  width. 

Habitat:  Intestine  Host:  Gallinago  wilsoni 

Locality:  Creston,  Iowa  Date:  August  4,  1894 

Collector:  W.  C.  Hall  No.  21.89  Ward  Collection 

The  direct  relationship  of  this  species  is  not  so  readily  apparent.  As 
to  position  of  the  genital  glands  it  holds  a  place  close  to  Cyclocoelum 
tringae  (Brandes)  and  Cyclocoelum  triangularum  nov.  spec,  and  tho  it  is 
much  larger  presents  in  general  the  same  characteristic  features  namely: 
genital  glands  contiguous,  uterine  loops  directed  backward,  vitellaria 
moderately  deveoped,  oral  sucker  larger  than  pharynx.  However,  in  the 
size  of  the  body  and  the  relative  size  of  the  pharynx  and  sucker  as  well  as 
the  relative  size  of  the  genital  glands  Cyclocoelum  wilsoni  is  clearly  distinct 
and  must  be  recognized  as  a  proper  species. 

CYCLOCOELUM  CUNEATUM  nov.  spec. 
[Figures  7,  24] 

Medium  sized  worms  10.5  to  12  mm  in  length  by  2.5  to  3.5  mm  in 
greatest  width  which  is  found  at  the  beginning  of  the  posterior  body 
fourth.  From  the  point  of  maximum  width  the  margins  of  the  body  run 
approximately  parallel  to  the  level  of  the  anterior  testis  at  which  point 
they  narrow  abruptly  to  form  the  obtusely  rounded  posterior  end.  From 
the  point  of  greatest  width  the  margins  of  the  body  converge  cephalad  in 
almost  straight  lines  to  a  very  narrow  and  pointed  anterior  end,  which 
gives  the  impression  of  a  well  formed  wedge.  At  the  pointed  anterior  end 
is  found  a  very  small  weakly  developed  sucker,  198  to  215/z  in  diameter. 
This  is  followed  by  an  oblong  pharynx  of  approximately  the  same  width 
as  the  sucker.  It  measures  150  to  198/i  in  width  by  215  to  231 /i  in  length. 
The  esophagus  is  three  and  one-half  to  four  times  the  length  of  the  pharynx. 
The  intestinal  crura  are  simple.  The  vitelline  glands  extend  from  the 
middle  region  of  the  bifurcation  of  the  intestine  to  the  excretory  bladder 


42  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [260 

in  the  posterior  end.  In  lateral  extent  they  rarely  traverse  the  outer 
wall  of  the  crura.  The  genital  opening  is  located  anterior  to  the  pharynx. 
The  cirrus  pouch  extends  to  the  anterior  wall  of  the  intestinal  bifurcation. 
The  uterus  fills  out  the  entire  space  between  the  crura  and  its  loops  occa- 
sionally span  the  outer  wall  of  the  same  organ.  The  genital  glands  are 
relatively  small  and  occupy  the  positions  so  common  to  the  species  of  this 
genus.  The  posterior  testis,  not  filling  out  the  intestinal  arch,  is  antero- 
posteriorly  flattened  and  measures  413  p.  in  width  by  496  to  612  p  in  length. 
The  anterior  testis  is  separated  from  the  posterior  by  several  uterine 
loops  and  is  smaller  and  spherical,  measuring  331  to  413ju  in  diameter. 
The  spherical  ovary  is  situated  in  a  transverse  plane  anterior  to  and  about 
equally  distant  from  the  two  testes.  It  is  one-fourth  smaller  than  the 
testes  measuring  215  to  331  p  in  diameter.  The  shell  gland  lies  median 
and  posterior  to  the  ovary,  is  spherical  or  only  slightly  ovoid  and  equal 
in  size  to  the  latter  organ.  The  receptaculum  seminis  although  indis- 
tinguishable in  to  to  mounts  is  clearly  seen  in  sections.  It  is  anterior  and 
dorsal  to  the  ovary.  Wax  reconstructions  show  it  to  be  spherical  and 
approximately  one-half  the  size  of  the  ovary,  measuring  150/*  in  diameter. 
The  ovarian  complex  is  separated  from  the  testes  by  uterine  loops.  The 
eggs  are  thick  shelled  ovals,  66 /z  wide  by  115/z  to  122 n  long. 

Habitat:  Abdominal  cavity  Host:  Gallinago  delicata  (Ord.) 

Locality:  ?  Date:  ? 

Collector:  ?  No.  08.  172  Ward  collection. 

The  relationships  of  this  species  is  not  so  evident  as  it  partakes  of  the 
characteristics  of  a  number  of  species.  With  respect  to  the  lateral  extent 
of  the  uterine  loops  it  is  more  nearly  like  Cyclocoelum  mutabile  and  Cyclo- 
coelum  leidyi  while  in  development  of  the  vitellaria  it  simulates  Cyclocoelum 
halli.  The  pharynx  and  oral  sucker  are  noticeably  smaller  than  in  any 
known  species  of  this  genus  and  this  is  a  feature  of  this  species  as  is  also 
the  small  size  of  the  genital  glands  and  the  proportionate  size  of  the  testes 
to  the  ovary,  a  ratio  of  4:3. 

CYCLOCOELUM  OBSCURUM  (Leidy) 

[Figures  8,  21] 

Syn:  Monostomum  obscurum  Leidy  1887 

This  species  was  described  by  Leidy  as  follows:  "Elongated,  elliptical, 
flattened,  obtusely  angular  in  front,  obtusely  rounded  behind,  oral  and 
genital  and  other  aperatures  scarcely  distinguishable.  Length  4  to  8  lines; 
width  1  line." 

"Numerous  specimens  in  the  stomach  of  a  Jew-fish,  Megalops  thris- 
soides" 

The  host  name  Megalops  thrissoides  used  for  the  Jew-fish  by  Leidy 
1887  is  evidently  a  lapsus  calami.  However  this  is  corrected  by  Stiles  and 
Hassall  (1894)  to  Stereolepis  sp? 


261]  NORTH  AMERICAN  MONOSTOMES  43 

Brandes  (1892)  enumerates  this  among  other  species  which  he  has 
not  had  opportunity  to  study  and  he  justly  says  that  it  is  inadequately 
described.  Monticelli  (1892)  and  Braun  (1893)  in  spite  of  the  meager 
description  retain  it  as  a  valid  species. 

The  original  material  of  this  species  is  found  in  the  Army  Medical 
Museum  under  Number  1035  Comparative  Anatomy  Series  with  the 
description  "Flukes  Monostomum  obscurum  from  the  stomach  of  a  Jew- 
fish  (Stereolepis)."  From  this  I  have  written  the  following  description. 

Monostomes  of  medium  size  measuring  from  6  to  13  mm  in  length  and 
from  1 . 5  to  3  mm  in  maximum  width  which  is  found  a  little  posterior  to 
the  middle  of  the  body.  The  margins  of  the  body  are  almost  parallel  for 
the  greater  part  of  their  length,  tapering  gently  to  the  more  pointed 
anterior  end  and  abruptly  to  form  the  obtusely  rounded  posterior  end.  As 
in  most  species  of  this  genus  the  body  is  convex  dorsally  and  flat  or  slightly 
concave  ventrally.  The  sub  terminal  mouth  is  surrounded  by  a  weakly 
developed  sucking  musculature  which  measures  115/z  in  diameter.  This 
leads  to  the  spherical  or  slightly  elongated  pharynx,  measuring  115  to 
264  ju  in  width  by  115  to  298  ju  in  length.  Following  this  the  slender  esopha- 
gus, 500  to  750/z  in  length,  leads  to  the  intestinal  bifurcation.  The  crura 
are  quite  variable  in  size  as  well  as  in  the  character  of  the  median  wall. 
In  some  cases  they  show  a  tendency  to  the  formation  of  internal  ceca;  these 
appear  to  be  due  to  the  pressure  from  the  closely  packed  uterus  which  fills 
the  space  between  the  crura.  The  excretory  system  in  this  species  has  not 
been  made  out  except  for  the  single  termnal  excretory  vesicle  situated  as 
in  the  other  species  of  this  genus  between  the  posterior  arch  of  the  intes- 
tinal crura  and  the  posterior  body  wall.  It  opens  to  the  exterior  by  a  single 
dorsal  pore.  The  genital  organs  lie  within  the  intestinal  crura  in  the 
posterior  end  of  the  body.  The  posterior  testis,  filling  the  posterior  arch 
of  the  intestine,  is  flattened  anteriorly  by  the  closely  packed  uterine 
loops  and  is  slightly  larger  than  the  anterior  being  300  to  877 n  in  width 
by  480  to  lOOOju  in  length.  The  anterior  testis  is  usually  more  nearly 
spherical  and  measures  380  to  827/x  in  width  by  462  to  827/i  in  length. 
It  lies  obliquely  anterior  to  the  posterior  and  adjacent  to  the  crura.  The 
vasa  efferentia  are  short  and  unite  a  short  distance  anterior  to  the  anterior 
testis  to  form  the  vas  deferens  which  for  the  most  part  passes  dorsal  to  the 
uterus  to  the  cirrus  pouch.  This  organ  is  of  medium  size  248  to  579/i  in 
length  by  115  to  199 ju  in  width.  In  general  its  posterior  limit  lies  on  a 
level  with  the  middle  of  the  intestimal  bifurcation.  The  ovarian  complex 
lies  between  the  testes  and  on  the  side  opposite  to  the  anterior  testis. 
It  is  composed  of  a  spherical  ovary,  275  to  463 /x  in  diameter,  a  spherical 
receptaculum  seminis,  132  to  148/z  in  diameter,  and  a  shell  gland  in  size 
and  form  similar  to  the  ovary.  The  position  of  these  is  clearly  shown  in 
figure  21.  Beginning  in  the  shell  gland  the  uterus  immediately  upon 


44  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [262 

emergence  enlarges  to  form  the  large  receptaculum  seminalis  uterinum. 
It  fills  the  intercecal  space  with  more  or  less  regular  loops  which  in  general 
go  out  from  the  middle  of  the  body.  These  loops  fold  around  the  inner 
surface  of  the  crura  and  usually  do  not  pass  beyond  the  outer  wall  of  the 
latter  organ.  The  vitellaria  for  the  most  lie  outside  the  crura  and  extend 
from  the  pharynx  to  the  excretory  bladder.  Laterally  they  reach  to  the 
middle  of  the  crura  and  in  exceptional  instances  to  the  inner  wall  of  that 
organ. 

Habitat:  Stomach  Host:  Stereolepis  sp? 

Locality:  ?  Date:  ? 

Collector:  ?  Cat.  No.  1035  Comparative 

Anatomy  series. 

Habitat:  ?  Host:  Symphaemia  semipalmata 

Locality:  Lincoln,  Nebraska  Date:  ? 

Collector:  ?  Cat.  No.  08 . 179  Ward  collection 

Habitat:  ?  Host:  Unknown 

Locality:  Spokane,  Wash.  Date:  ? 

Collector:  W.  E.  Allen  Cat.  No.  08 . 183  Ward  collection 

Cyclocoelum  obscurum  is  most  closely  related  to  Cyclocoelum  oiiopuncta- 
tum  Stossich  and  differs  from  that  species  in  the  more  slender  form,  the 
more  heavily  developed  vitellaria  and  the  relative  size  of  the  testes  to  the 
ovary  which  in  Cyclocoelum  obscurum  are  twice  as  large  as  the  ovary  while 
in  Cyclocoelum  ovopunctatum  they  are  three  times  as  large. 

CYCLOCOELUM  MACRORCHIS  nov.  spec. 
[Figure  9] 

This  species  varies  in  length  from  7  to  15  mm  and  in  maximum  width, 
which  is  found  just  posterior  to  the  middle  of  the  body,  from  2  to  4  mm. 
From  this  point  the  body  tapers  towards  both  ends,  the  posterior  being 
obtusely  rounded  while  the  anterior  is  considerably  more  attenuated. 
It  forms  a  moderately  rounded  point.  The  margins  of  the  body  lie  nearly 
parallel  in  the  middle  region  of  the  body.  The  subterminal  mouth  is  sur- 
rounded by  a  weakly  developed  musculature,  the  oral  sucker,  which  is 
only  a  little  larger  than  the  well  developed  pharynx  just  posterior  to  it, 
and  measures  255 /i  in  diameter.  The  pharynx  is  oval  in  shape  being  about 
one-fifth  longer  than  wide  and  measures  on  the  average  271/i  long  and 
238ju  wide.  The  esophagus  in  this  species  is  on  the  whole  well  extended 
and  ranges  from  331ju  in  the  state  of  least  extension  to  662  n  in  that  of 
greatest  extension  exhibited  in  preserved  material.  At  its  posterior  end 
the  esophagus  turns  ventrad  and  bifurcates  forming  the  voluminous 
crura  present  in  this  species  (Fig.  9).  These  as  in  other  species  of  this 
genus  lie  parallel  to  the  margins  of  the  body  and  anastomose  at  the  poster- 


263]  NORTH  AMERICAN  MONOSTOMES  45 

ior  end.  The  excretory  system  as  far  as  can  be  made  out  in  preserved 
material  conforms  in  this  species  to  the  description  given  previously  in 
having  a  single  thin  walled  vesicle  in  the  extreme  posterior  end  of  the  body 
into  which  the  anastomosing  tubules  empty.  It  opens  to  the  exterior 
slightly  dorsal  to  the  posterior  end.  The  genital  glands  in  general  occupy 
the  intercecal  zone  and  fill  entirely  that  space.  The  posterior  testis  occupies 
the  intestinal  arch,  is  usually  spherical  in  form  and  measures  783  to  984/i 
in  diameter.  The  anterior  testis  is  usually  removed  from  the  posterior  by 
several  uterus  loops.  It  is  spherical  and  approximately  the  same  size  as 
the  posterior  measuring  730  to  860 //  in  diameter.  As  in  other  species  of 
this  genus  the  vasa  efferentia  unite  cephalad  and  mesad  to  the  anterior 
testis.  From  this  point  the  vas  deferens  takes  its  course  among  the  uterine 
folds  to  the  posterior  end  of  the  cirrus  pouch  which  is  situated  at  the 
middle  of  the  intestinal  bifurcation.  The  cirrus  pouch  extends  from  the 
genital  atrium  caudad  to  the  middle  of  the  intestinal  bifurcation.  From 
this  point  the  club-shaped  cirrus  pouch  extends  cephalad  to  the  genital 
atrium  and  lies  ventral  to  the  anterior  end  of  the  pharynx.  The  ovarian 
complex  is  situated  between  the  testes  and  adjacent  to  the  crura  opposite 
the  anterior  testis.  The  ovary  is  spherical  and  measures  413  to  463/z  in 
diameter.  Dorsal  and  posterior  to  the  ovary  is  the  spherical  receptaculum 
seminis,  165/z  in  diameter.  The  duct  of  this  unites  with  the  oviduct 
before  it  enters  the  shell  gland.  The  shell  gland  is  approximately  the  same 
size  as  the  ovary  and  is  situated  posterior  and  dorsal  to  that  organ  (Fig. 
9).  The  well  developed  follicular  yolk  glands  occupy  the  region  of  the 
body  lateral  to  the  intestinal  crura  and  extend  from  the  anterior-most 
part  of  the  intestinal  bifurcation  to  the  posterior  end  where  they  are 
separated  only  by  the  small  excretory  bladder.  The  follicles  are  arranged 
in  clusters  on  secondary  branches  from  the  main  stem  and  in  this  manner 
extend  laterad  around  the  crura  both  dorsally  and  ventrally,  in  many 
cases  reaching  out  as  far  as  the  inner  wall  of  the  crura.  The  vitelline  ducts 
are  given  off  in  the  region  of  the  shell  gland  and  pass  mesad  to  a  point 
just  dorsal  to  the  shell  gland  where  they  unite  to  form  the  vitelline  reser- 
voir. From  this  the  common  vitelline  duct  passes  dorsal  to  the  shell  gland 
and  joins  the  oviduct  just  before  its  entrance  into  that  organ.  Immediately 
upon  entering  the  shell  gland  the  oviduct  enlarges  to  form  the  ootype. 
Upon  emergence  from  this  the  uterus  enlarges  to  form  the  receptaculum 
seminalis  uterinum.  From  this  point  the  much  folded  uterus  fills  out  the 
entire  space  between  the  crura  and  passes  over  the  bifurcation  in  a  relative- 
ly straight  stretch  to  the  genital  atrium.  The  numerous  eggs  which  fill  the 
uterus  are  thick  shelled  ovals,  measuring  from  122  to  153 M  in  length  by  56 
to  66  fj,  in  width.  In  general  the  eggs  are  smaller  in  the  beginning  of  the 
uterus  than  they  are  near  the  genital  orifice.  The  eggs  in  the  anterior 
region  show  well  developed  miracidia  with  double  dark  eye  spots. 


46  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [264 

Habitat:  In  lung  and  along  the  Host:  Straight-billed  Curlew 

back  in  the  abdomen. 

Collector:  W.  E.  Allen  No.  08 . 180  Ward  collection 

Cydocoelum  macrorchis  differs  from  Cyclocoelum  mutabile  in  that  the 
uterus  in  the  former  is  not  restricted  to  the  intercecal  space  and  that  the 
oral  sucker  is  larger  than  the  pharynx,  where  as  in  Cyclocoelum  mutabile 
the  vitellaria  are  more  heavily  developed  and  the  genital  glands  are  smaller. 
Cyclocoelum  macrorchis,  however,  has  a  much  more  muscular  and  much 
thicker  and  heavier  body. 

CYCLOCOELUM  TRIANGULARUM  nov.  spec. 
[Figure  10] 

Medium  sized  worms  8  mm  long  by  2.5  mm  wide  in  maximum.  Body 
lanceolate  in  form.  Oral  sucker  weak,  260/z  in  diameter,  only  a  little 
larger  than  the  pharynx  which  is  longer  than  broad,  measuring  248  n  in 
length  by  215  M  in  breadth.  The  length  of  the  esophagus  is  approximately 
one- tenth  of  the  entire  body  length.  Intestinal  crura  simple.  Genital 
pore  ventral  to  the  posterior  end  of  the  pharynx.  Cirrus  pouch  extending 
to  the  middle  of  the  intestinal  bifurcation.  The  vitellaria  extends  from  the 
posterior  end  of  the  cirrus  pouch  almost  to  the  excretory  bladder  at  the 
posterior  end  of  the  worm.  In  lateral  extent  they  pass  over  the  wall 
of  the  crura  to  the  middle  of  that  organ.  The  genital  glands  lie  in  the 
posterior  arch  of  the  intestine  and  are  not  separated  by  uterine  loops. 
The  two  testes  lie  on  the  same  level,  one  in  either  side  of  the  arch,  are 
spherical  and  equal  in  size.  They  measure  41 3  ^  in  diameter.  The  ovary 
lies  anterior  to  the  testes  and  in  the  middle  line  of  the  body.  It  is  a  little 
more  than  one-half  the  size  of  the  testes,  is  spherical  in  form  and  measures 
248  /z  in  diameter.  The  shell  gland  lies  between  the  ovary  and  testes  also 
in  the  middle  line  of  the  body  and  measures  264 ^  in  width  by  314/j  in 
length.  The  receptaculum  seminis  is  situated  anterior  to  the  shell  gland 
and  dorsal  to  the  ovary.  Like  the  ovary  the  receptaculum  seminis  is 
spherical  in  form  and  measures  132/*  in  diameter.  The  eggs  are  thick 
shelled  ovals  132 n  long  by  75 /i  wide. 

Habitat:  Abdominal  air  sacs  Host:  Tringa  maculata 

Locality:  Creston,  Iowa  Date:  September  4,  1895 

Collector:  W.  C.  Hall  No.  21.88  Ward  collection 

As  was  stated  in  another  section  of  this  paper  Cyclocoelum  triangularum 
shows  a  striking  similarity  to  Cyclocoelum  wilsoni  and  is  distinguished  from 
that  species  by  the  generally  smaller  body,  the  more  nearly  equal  sucker 
and  pharynx,  the  testes  of  equal  size  and  the  relative  size  of  the  testes  and 
ovary  which  in  Cyclocoelum  triangularum  have  a  ratio  of  10:7.  It  is  more 
nearly  equal  in  size  with  Cyclocoelum  tringae  but  is  distinguished  from 


[265  NORTH  AMERICAN  MONOSTOMES  47 

this  species  by  the  larger  pharynx,  smaller  sucker,  the  testes  being  equal 
in  size  and  also  smaller  in  proportion  to  the  size  of  the  ovary. 

CYCLOCOELUM  VICARIUM  (Arnsdorff  1908)  Kossack  1911 

Syn:  Monostomum  mcarium  Arnsdorff 

The  writer  has  not  had  opportunity  to  study  specimens  of  this  species 
and  hence  must  rely  upon  the  descriptions  of  Arnsdorff  (1908)  and  Kossack 
(1911).  Since  the  description  of  Kossack  made  after  having  studied  the 
original  material  is  at  variance  with  the  original  description  only  in  minor 
detail  the  writer  has  based  the  following  description  on  the  work  of  Arns- 
dorff. 

Monostomes  varying  between  10.5  and  14.4  mm  in  length  and  3  to 
3.1  mm  in  maximum  breadth.  The  body  is  opaque,  flattened;  ventral 
surface  flat,  dorsal  slightly  swollen.  The  sidelines  of  the  body  diverge 
from  the  small  pointed  anterior  end  to  the  height  of  the  testes.  From  here 
they  form  the  bluntly  rounded  posterior  end.  The  dorsal  surface  of  the 
body  is  quite  wrinkled.  These  folds  appear  in  optical  section  to  form  pap- 
pillae.  The  mouth  opening  is  terminal.  The  strongly  muscular  pharynx  is 
an  elongate  oval  with  a  long  diameter  of  460  p  and  a  breadth  of  270/i. 
The  thickness  of  its  wall  is  130/*.  The  esophagus,  640 /A  long,  leads  to  the 
intestinal  crura  which  run  parallel  to  the  side  walls  of  the  body  and  anas- 
tomose in  the  posterior  end.  The  genital  organs  lie  in  the  broad  hinder 
end.  The  posterior  testis  is  flattened  antero-posteriorly  and  measures 
1190/z  in  length  by  732  p  in  breadth.  It  lies  in  the  middle  line  of  the  body 
with  its  forward  margin  reaching  to  the  vitelline  duct.  The  anterior  testi? 
is  spherical  in  form  with  a  diameter  of  835  to  878 p.  It  is  removed  anteriorly 
from  the  posterior  end  and  lies  adjacent  to  the  intestinal  crura.  The  ovary 
lies  adjacent  to  the  crural  wall,  opposite  to  the  anterior  testis  and  between 
the  positions  of  the  testes.  It  is  spherical  and  has  a  diameter  of  402 /x. 
Between  it  and  the  posterior  testis  is  found  the  relatively  small  recep- 
taculum  seminis. 

The  vitellaria  are  composed  of  numerous  follicles  which  lie  parallel  to 
the  body  wall  and  between  that  and  the  intestinal  crura;  they  extend  from 
the  region  of  the  intestinal  bifurcation  to  the  posterior  end  where  they  are 
separated  by  a  short  interval.  The  numerous  transverse  uterus  loops 
fill  out  the  space  between  the  crura  and  in  the  posterior  half  of  the  body 
overlap  them.  The  genital  pore  is  situated  just  posterior  to  the  pharynx. 
The  club-shaped  cirrus  pouch  is  small  and  does  not  reach  the  intestinal 
bifurcation.  The  eggs  are  numerous,  elliptical  in  form  and  measure  102 ./*  in 
length  and  68  n  in  breadth.  The  ripe  eggs  hold  a  well  developed  embryo 
as  can  be  recognized  by  the  black  eye  spots  in  the  miracidium. 


48  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [266 

The  comparison  of  Arnsdorff  with  the  figures  and  description  of  Stos- 
sich  for  closely  related  species  show  a  striking  similarity  to  Cydocoelum 
problematicum.  Cydocoelum  mcarium  differs  from  this  species,  however, 
in  the  relative  size  of  the  worms,  the  extent  of  the  cirrus  pouch  and  the 
size  of  the  eggs. 

Habitat:  Intestine  Host:  Arquatella  maritima  mari- 

tima 

Locality:  North  East  Labrador  Date:  September  14,  1906 

Collector:  Hantzsch  Konigsberg  Museum 

NOTOCOTYLIDAE  Liihe  1909 

Of  the  monostome  families  which  have  up  to  this  time  been  widely 
studied  no  other  family  is  of  greater  interest  than  the  Notocotylidae.  It 
is  in  this  family  that  the  earliest  records  of  the  monostomes  are  found  in 
Catatropis  verrucosa  (Frolich  1789)  collected  from  the  rectum  of  Anas 
domestica.  These  worms  were  classed  by  Frolich  and  Gmelin  as  Fasciola. 
Ten  years  later  Zeder  (1800)  removed  them  to  the  genus  Monostoma. 
They  were  later  separated  from  the  remaining  monostomes  by  Diesing 
(1839)  and  placed  in  a  new  genus  Notocotylus  which  genus  remains  as  the 
type  of  the  family.  Although  Diesing  included  this  earliest  known  form  in 
his  genus  Notocotylus,  it  has  been  found  in  more  recent  time  by  Odhner 
(1905)  to  be  distinct  from  the  Diesing  type  species,  Notocotylus  triserialis, 
and  was  removed  to  the  new  genus  Catatropis  which  place  it  holds  at  pre- 
sent as  type  of  that  genus.  A  further  study  of  Notocotylus  triserialis  Diesing 
by  Kossack  (1911)  revealed  its  identity  with  Monostomum  attenuatum 
Rud.  1809.  Thus  the  species  name  becomes  a  synonym  to  Notocotylus 
attenuatus. 

In  regard  to  the  early  records  of  this  family  in  America  there  still 
remains  a  question.  Some  authors  notably  Barker  and  Laughlin  would 
place  Monostomum  affine  Leidy  1858  as  the  earliest  American  record  while 
others  doubt  this  determination  and  still  others  reserve  opinion  on  the 
matter.  Barker  (1916)  questions  the  determination  of  Leidy  and  expresses 
the  opinion  that  Monostomum  affine  Leidy  belongs  to  the  genus  Notocoty- 
lus. While  the  description  of  Leidy  (1858:110-112)  is  insufficient  for  an 
accurate  determination  of  the  systematic  position  of  this  species  certain 
facts  given  in  his  description  are  distinct  and  seem  sufficient  to  show  that 
this  worm  is  not  Notocotylid  in  character.  The  length  of  Monostomum 
affine  as  given  by  Leidy  is  6}^  lines  or  13.5  mm  which  is  two  and  one-half 
to  three  times  longer  than  any  known  species  of  this  family.  Likewise  on 
the  same  basis  the  Leidy  species  is  at  least  three  times  wider  than  the 
largest  known  Notocotylid.  However,  more  important,  intrinsic  charac- 
ters are  the  presence  of  a  pharynx,  an  echinate  penis  and  eggs  prolonged  at 
one  pole  only.  In  addition  these  worms  were  taken  from  the  gall-bladder 


267]  NORTH  AMERICAN  MONOSTOMES  49 

and  bile  ducts  of  the  muskrat  while  the  Notocotylidae  are  normally 
inhabitants  of  the  intestine  and  rectum.  It  is  not  impossible  that  a  Noto- 
cotylid  species  may  have  ascended  the  gall-duct  of  this  host  and  become 
modified  and  adjusted  to  the  new  conditions.  Yet  on  the  basis  of  the  facts 
noted  above  the  writer  cannot  agree  with  the  opinion  of  Barker  regarding 
the  Notocotylid  character  of  these  worms. 

More  recently  Hassall  (Stiles  &  Hassall  1894)  collected  from  Arvicola 
riparius  and  Fiber  zibethicus  taken  in  Maryland  in  1892  specimens  deter- 
mined as  Monostomum  sp.  and  one  year  later  from  Aix  sponsa  and  Dafila 
acuta  worms  also  determined  as  Monostomum  sp.  On  observation  and 
study  by  the  writer  the  specimens  taken  from  Aix  sponsa,  Dafila  acuta 
and  Fiber  zibethicus  have  been  found  to  be  distinctly  different  from  forms 
previously  described  and  on  the  basis  given  in  a  later  section  must  be 
recognized  as  a  new  species.  On  account  of  the  similarity  to  the  immature 
stages  of  Cercaria  urbanensis  Cort  it  is  believed  to  be  the  adult  form  of  this 
species.  The  material  taken  from  Arvicola  riparius  has  been  found  to 
agree  with  Notocotylus  quinqueserialis  (Barker  and  Laughlin  1911).  Other 
American  records  are  those  of  Barker  (1915,  1916)  in  which  he  records 
Catatropis  filamentis  from  Fiber  zibethicus  taken  in  Nebraska  and  Nudoco- 
tyle  novicia  from  the  same  host  taken  in  the  same  region. 

Additional  records  presented  in  this  paper  are  Notocotylus  urbanensis 
(Cort  1914)  from  the  black  and  domestic  swan  taken  at  Golden  Gate 
Park,  San  Francisco,  California  by  John  C.  Johnson  in  February  1919  and 
Paramonostomum  echinum  nov.  spec,  from  the  intestine  of  Fiber  zibethicus 
taken  at  Wray,  Colorado  by  C.  H.  Gable,  October  1916. 

DIAGNOSIS  OF  FAMILY 

Small  monostomes  tapering  at  both  ends,  posterior  end  broadly 
rounded,  anterior  slightly  more  attenuated.  Generally  with  rows  of  papil- 
lae formed  of  unicellular  dermal  glands.  Esophagus  short,  without 
pharynx;  intestinal  ceca  with  short  diverticula,  extending  entire  length  of 
body.  Genital  pore  median,  except  in  Nudocotyle  where  it  is  distinctly 
lateral,  usually  near  oral  sucker.  Cirrus  sac  elongate.  Testes  symmetrical, 
extracecal,  near  posterior  end.  Ovary  between  testes.  Vitellaria  lateral, 
anterior  to  testes.  Uterine  coils  between  cirrus  sac  and  genital  glands, 
transverse,  regular,  usually  not  extending  outside  intestinal  crura.  Eggs 
small  with  long  p  olar  filament  on  each  end. 

KEY  TO  SUBFAMILIES  AND  GENERA 

1(5)  Genital  pore  anterior  median.  .  .Sub-family  Notocotylinae .  . 2 

2(5)  With  ventral  glands ." 3 

3(4)  Ventral  glands  protrusible Notocotylus  Diesing  1839 

4(3)  Ventral  glands  not  protrusible Catatropis  Odhner  1905 


50  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [268 

5(2)     Ventral  glands  wanting Paramonostomum  Liihe  1909 

6(1)     Genital  pore  marginal  posterior  without  ventral  glands .... 

Sub-family  Nudocotylinae  . .  7 

Uterus  in  anterior  body  half Nudocotyle  Barker  1916 

The  Notocotylidae  are  up  to  the  present  represented  in  North  America 
by  two  species  of  Notocotylus  and  one  species  of  each  of  the  other  genera  in 
this  family. 

The  Notocotylidae  were  subdivided  by  Kossack  (1911)  into  two  sub- 
families; Notocotylinae  including  Notocotylus  Diesing  (1839)  Catatropis 
Odhner  (1905)  and  Paramonostomum  Liihe  (1909),  and  Ogmogasterinae 
represented  by  a  single  species  Ogmogaster  plicatus  (Creplin  1829)  Jager- 
skiold  1891.  A  third  subfamily  Nudocotylinae  was  created  by  Barker 
(1916)  to  hold  Nudocotyle  nomcia.  In  this  Barker  would  include  Barisomum 
erubescent  Linton  (1910). 

NOTOCOTYLINAE  Kossack  1911 

Small  to  medium  sized  Notocotylidae  with  thin  cup-shaped  body;  two 
to  five  rows  of  prominent  papillae  on  ventral  surface.  Genital  pore  median, 
near  intestinal  bifurcation.  Cirrus  pouch  enclosing  only  a  small  part  of 
seminal  vesicle.  Vitellaria  well  developed  occupying  a  region  posterior 
to  middle  portion  of  body  anterior  to  testes  and  lateral  to  intestinal  crura. 
Ovary  and  testes  symmetrical,  in  extreme  posterior  part  of  body.  Ovary 
between  testes  and  separated  from  them  by  intestinal  crura.  Uterus  regu- 
larly coiled,  between  intestinal  crura. 

Type  genus  Notocotylus.  Other  American  genera  Catatropis  and 
Paramonostomum. 

NOTOCOTYLUS  Diesing  1839 
Syn:  Notocotyle  Diesing  1850 

The  genus  Notocotylus  was  formed  by  Diesing  in  1839  to  include 
Fasciola  verrucosa  Frolich,  Fasciola  anseris  Gmelin,  Festucaria  pedata 
Schrank  and  Monostoma  verrucosum  Zeder.  It  was  characterized  by  the 
author  as  follows:  "Corpore  oblonga-ovato,  depressiuscula,  antice  parum 
attenuate,  postice  rotundato,  ore  terminali  orbiculari;  acetabulis  suctoriis 
dorsalibus  numerosis,  serie  triplici  longitudinali;  cirro  longo  spirali  ven- 
trali."  In  1850  the  author  changed  the  name  to  Notocotyle  with  only  a 
slightly  modified  diagnosis  as  follows:  "Corpus  oblongum  depressum. 
Caput  corpore  continuum.  Os  subterminale  anticum.  Acetabula  numerosa 
(24-50)  juxta  totam  dorsi  convexiusculi  longitudinem  treseriata  sissilia, 
orbicularia,  limbo  callosa.  Penis  ventralis  superus  longi  spiralis.  Porus 
excretorius  ....  In  avium  intestinis  crassis  et  coecis  endoparasita!" 
Under  this  caption  Diesing  included  his  former  genus  Notocotylus.  Altho 
Monticelli,  Barker  and  others  adhere  to  the  more  recent  form  of  the  name 


269]  NORTH  AMERICAN  MONOSTOMES  51 

the  writer  feels  justified  under  Article  32  of  the  International  Rules  of 
Zoological  Nomenclature  in  accepting  with  Kossack,  Ward  and  others  the 
older  name  Notocotylus. 

This  genus  is  up  to  the  present  represented  in  America  by  a  single  spe- 
cies Notocotylus  quinqueserialis  (Barker  and  Laughlin).  Altho  Barker 
(1916)  would  place  Monostomum  qffine  Leidy  in  this  group,  his  determina- 
tion seems  to  be  unwarranted  on  the  basis  of  the  description  of  Leidy  which 
shows  distinct  anatomical  differences  namely  a  small  pharynx,  echinate 
penis,  a  well  marked  excretory  canal  traceable  to  the  beginning  of  the 
oviduct,  and  sub-pyriform  eggs  prolonged  at  one  pole  only.  In  addition  to 
the  anatomical  differences  Monostomum  affine  was  found  parasitic  in  the 
gall  bladder  and  gall  ducts  of  Fiber  zibethicus  whereas  Notocotylus  has  been 
taken  only  from  the  intestine  and  ceca  of  the  muskrat  and  water  birds. 

NOTOCOTYLUS  URBANENSIS  (Cort  1914) 

[Figures  12,  14,  17,  18,  19] 
Syn:  Monostoma  sp.  Stiles  and  Hassall  1894 

Medium  sized  worms  2.5  to  3 . 5  mm  long  by  0. 5  to  1  mm  wide,  having 
three  rows  of  ventral  glands  each  row  containing  13  to  14  glands.  Oral 
sucker  strongly  muscular  112  to  153  n  followed  by  a  short  esophagus  with- 
out pharynx;  intestinal  crura  provided  with  numerous  short  diverticula 
both  externally  and  internally.  Genital  pore  just  posterior  to  intestinal 
bifurcation.  From  this  point  the  cirrus  pouch  extends  caudad  to  the  end 
of  the  first  body  third  or  a  little  beyond  this  level.  Vagina  one-half  the 
length  of  the  cirrus.  Usually  about  ten  uterine  loops  anterior  to  the  most 
anterior  part  of  the  vitellaria  which  as  in  other  species  of  the  genus  lie 
lateral  to  the  ceca  and  extend  from  the  middle  of  the  body  to  the  lobed 
testes  in  the  posterior  end.  The  irregularly  lobed  ovary  is  situated  between 
the  testes  and  is  separated  from  them  by  the  crura.  Eggs  numerous  pos- 
sessing two  long  polar  filaments.  Eggs  without  filaments  measure  20/*  in 
length,  and  are  approximately  one-half  that  in  width. 

Habitat:  Intestine  Host:  Dafila  acuta 

Locality:  Maryland  Collector:  A.  Hassall 

Date:  January,  1893  No.  5772  U.S.N.M. 

Habitat:  Cecum  Host:  Fiber  zibethicus 

Locality:  Maryland  Collector:  A.  Hassall 

Date:  June  23,  1892  No.  5769  &  5770  U.S.N.M. 

Habitat:  Intestine  Host:  Aix  sponsa 

Locality:  Maryland  Collector:  A.  Hassall 

Date:  August,  1893  No.  5771  U.S.N.M. 

Notocotylus  urbanensis  agrees  with  Notocotylus  attenuatus  in  size  and 
form,  and  in  the  relative  length  of  the  cirrus  pouch  and  vagina.  With 
respect  to  the  number  of  papillae  in  each  row  it  conforms  more  closely 


52  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [270 

to  Notocotylus  aegyptiacus ;  it  differs,  however,  from  this  species  in  the 
relative  length  of  the  cirrus  pouch  and  vagina.  In  the  position  of  the 
genital  pore  it  agrees  with  Notocotylus  seineti  Fuhr.  and  in  this  respect  it 
differs  from  other  known  species  of  this  genus. 

Stages  in  the  Life  History 

Three  collections  No.  5769,  5770,  and  5771  of  the  United  States 
National  Museum  contain  immature  forms  of  this  species.  Collection  No. 
5771  contains  both  immature  and  sexually  mature  worms.  The  very  young 
stages  found  in  the  two  collections  from  the  muskrat  agree  so  well  with 
the  immature  forms  from  Aix  sponsa  that  it  is  impossible  to  differentiate 
the  two  forms  and  consequently  they  are  taken  to  be  identical. 

The  most  immature  specimens  have  apparently  just  burst  out  of  the 
cysts  since  the  pigmentation  can  be  seen  quite  as  perfectly  as  in  most 
Notocotylid  oercariae.  The  pigmentation  in  this  species  agrees  generally 
with  that  described  by  Cort  (1914)  for  Cercaria  urbanensis.  The  pig- 
mentation remaining  is  arranged  around  the  lateral  eye  spots  (Fig.  19)  and 
the  lateral  pigmented  lines  extending  from  the  eye  spots  to  near  the 
posterior  end.  Aside  from  this  there  is  a  very  diffuse  pigmentation  through- 
out the  entire  body.  From  the  time  of  encystment  of  the  cercaria  to  the 
youngest  stages  at  hand  considerable  change  has  taken  place.  The 
anterior  eye  spot  has  been  lost  and  the  general  pigmentation  as  described 
above  is  generally  much  reduced  as  compared  with  the  heavily  pigmented 
Cercaria  urbanensis.  The  locomotor  pockets  have  been  resorbed  so  that 
no  trace  of  them  exists  in  the  youngest  stages  at  hand.  Development  of 
the  ventral  glands  is  the  most  conspicuous  change  which  has  taken  place. 
Figure  14  shows  diagrammatically  the  youngest  stage  studied  in  which 
three  ridges  or  keels  are  thrown  out  on  the  ventral  side.  The  median  one 
being  about  twice  as  high  as  the  lateral  ones  which  are  ventral  in  position 
to  the  intestinal  crura  (Fig.  12).  Along  the  median  ridge  the  papillae 
altho  only  partially  differentiated  are  clearly  seen.  The  lateral  ridges 
show  indistinct  irregularities  which  in  section  are  clearly  the  beginnings 
of  the  papillae.  No  trace  of  the  outer  rows  of  papillae  which  occur  in 
Notocotylus  quinqueserialis  have  been  observed.  In  more  mature  stages 
the  ventral  papillae  are  distinctly  seen  (Figs.  17,  19). 

Faust  (1918)  stated  that  in  the  Monostomata  the  paired  ceca  are 
filled  with  a  jell  and  are  nonfunctional  in  the  cercaria  stage.  In  contrast 
to  this  the  ceca  in  the  youngest  stages  studied,  which  are  of  course  well 
past  the  cercaria  stages  Faust  studied,  show  that  changes  have  taken 
place  in  this  feature.  The  ceca  in  these  stages  show  the  intestine  as  a  tube 
(Fig.  12)  whose  walls  are  surrounded  by  large  nucleated  cells.  Totos  in 
this  stage  of  development  also  show  distinct  but  small  internal  and  external 
diver ticula  (Fig.  19). 


271]  NORTH  AMERICAN  MONOSTOMES  53 

The  genital  glands  show  little  development  over  that  of  the  cercariae. 
The  ovary  and  testes  are  made  out  readily  in  the  toto  mount  as  well  as  the 
cords  of  cells  which  are  to  differentiate  into  uterus,  vagina,  vas  deferens 
and  cirrus.  In  more  mature  stages  differentiation  of  the  cirrus  and  vagina 
is  well  started  so  that  the  relative  length  of  the  two  organs  can  be  deter- 
mined. 

In  the  more  mature  specimens  represented  in  figure  17  the  genital 
glands  have  made  a  tremendous  growth  and  appear  very  much  as  in  the 
sexually  active  worm.  The  uterus,  however,  is  less  distinct  and  probably 
still  non-functional.  It  is  in  this  stage  that  the  vitelline  glands  make  their 
first  appearance  and  here  appear  as  single  celled  isolated  follicles.  The 
ducts  of  these  follicles  cannot  be  traced  so  that  it  is  impossible  to  determine 
if  the  relation  found  by  Faust  (1918),  namely  that  the  vitellaria  of  Notoco- 
tylids  are  composed  of  five  inner  and  three  outer  portions,  obtains  in  this 
species. 

Of  the  seven  larval  Monostomata  described  from  North  America,  viz. 
Cer carlo,  hyalocauda  Haldemann  1842  Cercaria  konadensis  Faust  1918 
Glenocercaria  lucania  Leidy  1877  Cercaria  aurita  Faust  1918 

Cercaria  urbanensis  Cort  1914  Cercaria  robusta  Faust  1918 

Cercaria  pellucida  Faust  1918 

the  immature  stages  described  above  resemble  more  closely  Cercaria  ur- 
banensis Cort  (1914)  than  any  other  known  monostome  cercaria.  Based  on 
the  similarity  of  the  excretory  system,  of  the  genital  organs,  on  the  pig- 
mentation and  on  the  late  differentiation  of  the  vitellaria,  no  trace  of  which 
has  yet  been  found  in  Cercaria  urbanensis,  it  seems  highly  probable  that 
these  forms  can  be  actually  connected.  Hence  while  demonstration  of  the 
life  history  by  experimental  methods  has  not  at  this  time  been  given,  it 
seems  justifiable  to  accept  Cercaria  urbanensis  as  the  larval  form  of  this 
Notocotylid. 

NOTOCOTYLUS  QUINQUESERIALIS  (Barker  and  Laughlin) 

Syn:  Monostoma  sp.  Stiles  and  Hassall  1894 

Notocotyle  quinqueseriale  Barker  and  Laughlin  1911 

Medium  sized  to  large  Notocotylids  with  wedge  shaped  body  2 . 5  to 
4  mm  long  by  0 . 66  to  1 . 33  mm  in  maximum  width  which  is  found  at  the 
level  of  the  ovary.  Anterior  end  more  or  less  pointed,  posterior  end 
rounded.  Dorsal  surface  smooth,  convex,  ventral  concave,  unarmed  but 
possessing  five  longitudinal  rows  of  adhesive  glands  or  papillae.  Each 
row  containing  from  16  to  18  distinct  wart-like  projections.  Mouth  sub- 
terminal,  spherical  200  to  450 M  in  diameter;  esophagus  short  without  phar- 
ynx. Intestinal  crura  irregular  in  shape  and  size  with  short  internal  and 
external  diverticula.  Genital  pore  between  mouth  and  intestinal  bifurca- 


54  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [272 

tion.  Cirrus  pouch  extending  from  this  point  into  the  beginning  of  the 
second  body  third,  being  approximately  one-third  the  length  of  the  entire 
body.  Vagina  two-thirds  the  length  of  the  cirrus  pouch.  The  much  lobed 
testes  are  situated  in  the  posterior  end,  external  to  the  intestinal  crura. 
Ovary  irregularly  lobed,  on  a  level  with  and  between  the  testes,  intracecal 
in  position.  Vitellaria  extracecal,  anterior  to  the  testes,  extending  to  the 
middle  of  the  body. 

Habitat:  Intestine  Host:  Armcola  riparius 

Locality:  Maryland  Collector:  A.  Hassall 

Date:  1892  No.  5773  U.S.N.M. 

Habitat:  Intestine  Host:  Fiber  zibethicus 

Locality:  Baker  Lake,  Washington     Collector:  H.  E.  Metcalf 
Date:  August  13,  1915  No.  15.120  Ward  collection 

The  description  of  Barker  and  Laughlin  while  adequate  states  that  the 
intestinal  ceca  are  simple.  A  careful  examination  of  the  material  at  hand 
shows  small,  short  diverticula  both  externally  and  internally  throughout 
the  length  of  the  ceca.  The  writer  has  not  had  opportunity  to  study 
the  material  described  by  Barker  and  Laughlin. 

CATATROPIS  Odhner  1905 

Body  elongate,  anterior  and  posterior  ends  usually  equally  rounded. 
Anterior  half  of  ventral  surface  covered  with  three  rows  of  non-protrusible 
papillae;  median  row  set  on  a  ridge  or  keel;  lateral  rows  each  containing  8 
to  12  glands.  Vagina  strongly  developed,  usually  as  long  as  the  cirrus 
pouch. 

This  genus  was  created  by  Odhner  to  hold  Catatropis  verrucosa  (Fro- 
lich)  which  Odhner  found  to  differ  from  Notocotylus  in  the  character  of 
the  ventral  glands,  those  of  Notocotylus  being  protrusible  while  those  found 
in  Catatropis  verrucosa  were  very  much  reduced,  being  in  the  form  of  a 
median  ridge  or  keel  in  the  median  row  and  small  embedded  papillae  or 
glands  in  the  outer  rows.  It  is  similar  to  Notocotylus  in  its  inner  organiza- 
tion and  differs  from  that  genus  in  the  fact  that  the  ventral  glands  are  not 
protrusible. 

CATATROPIS  FILAMENTIS  Barker  1915 
Syn:  Catatropis  fimbriata  Barker  1915 

Th,m  flat  worms,  gradually  tapering  anteriorly,  2.2  to  3.3  mm  long 
by  0 . 56  to  0 . 7  mm  wide  at  the  level  of  the  testes.  Anterior  half  of  the  body 
covered  with  needle  like  spines  arranged  in  oblique  rows.  Three  rows  of 
flattened  papillae  on  the  ventral  surface,  12  to  13  in  each  row.  Oral  sucker 
spherical,  66  to  99/x  in  diameter.  Esophagus  105  to  132 /^  in  length. 
Pharynx  wanting.  Intestinal  crura  undulating.  Testes  two  to  four  lobed, 
external  to  the  intestinal  crura.  Ovary  globular  or  oval  132 ^  long  by  105 


273]  NORTH  AMERICAN  MONOSTOMES  55 

to  112/j  wide,  margin  irregular.  Shell  gland  ovoid,  anterior  to  and  a  little 
larger  than  the  ovary.  Cirrus  pouch  tubular,  elongate,  extending  to  the 
beginning  of  the  second  body  third.  Prostate  gland  and  cirrus  covered 
with  papillae.  Vagina  straight,  muscular,  as  long  as  the  cirrus  pouch. 
Vitellaria  external  to  the  ceca,  extending  from  the  middle  of  the  body 
caudad  to  the  testes.  Excretory  bladder  forked,  opening  to  the  exterior 
just  dorsal  to  the  posterior  end.  Eggs  thick  shelled,  20  to  22 ju  long  by  llju 
wide,  having  two  long  polar  filaments,  one  at  each  end. 

Habitat:  Duodenum  Host:  Fiber  zibethicus 

Locality:  Nebraska  Collector:  ? 

PARAMONOSTOMUM  Luhe  1910 

This  genus,  created  by  Liihe  to  hold  Monostomum  alveatum  (Mehlis) 
Creplin,  is  characterized  by  Liihe  as  follows:  Body  compressed,  egg  shaped, 
greatest  breadth  a  little  caudad  from  middle  of  body,  posterior  end  broadly 
anterior  tapering  and  pointed;  anterior  half  of  ventral  surface  thick  set 
with  short  heavy  spines.  Ventral  glands  absent.  Cirrus  pouch  weakly 
muscular.  Vagina  usually  one-half  length  of  cirrus  pouch. 

Type  species:  Paramonostomum  alveatum  (Mehlis)  Crepl. 

American  representative:  Paramonostomum  echinum  nov.  spec. 

Barker  (1916)  criticises  the  erection  of  a  new  genus  on  the  basis  of  the 
absence  of  the  ventral  glands  on  the  ground  that  the  number  of  rows  vary 
from  two  in  Notocotylus  diserialis  Ssinitzin  to  five  in  Notocotylus  quinqueser- 
ialis  Barker  and  Laughlin.  Yet  the  same  author  accepts  the  genus  Catatro- 
pis  of  Odhner  founded  on  the  non-protrusible  character  of  these  same 
glands.  There  is  apparently  as  much  reason  to  accept  the  genus  of  Luhe 
based  on  their  absence  as  that  of  Odhner  founded  on  their  non-protrusi- 
bility. 

PARAMONOSTOMUM  ECHINUM  nov.  spec. 

Thin  cup-shaped  worms,  2  to  2 . 5  mm  in  length  by  0.6  to  0.7  mm  in 
maximum  width  which  is  found  at  the  beginning  of  the  posterior  third 
of  the  body  length.  No  ventral  papillae  have  been  found  on  these  worms, 
the  anterior  half  of  the  ventral  surface  being  covered  with  heavy  spines 
5/i  in  length.  These  curve  caudad  and  are  thick  set  according  to  the 
definite  pattern  shown  in  figures  13  and  16.  Mouth  terminal,  spherical, 
102  to  125ju  in  diameter,  followed  by  a  short  esophagus  which  bifurcates 
to  form  the  intestinal  crura;  these  follow  an  undulating  course  to  the 
posterior  end  of  the  body  where  they  end  blindly.  Crura  provided  with 
short  but  definite  internal  and  external  diverticula.  Genital  pore  situated 
just  posterior  to  the  intestinal  bifucation.  Cirrus  pouch  extends  from  this 
point  into  the  beginning  of  the  second  third  of  the  body.  Vagina  one-half 
as  long  as  the  cirrus  pouch.  Prostate  gland  and  cirrus  without  papillae. 


56  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [274 

Testes  four  lobed,  extracecal,  lying  at  the  same  level  in  the  posterior  end  of 
the  body.  Ovary  between  the  testes  and  separated  from  them  by  the 
intestinal  crura.  The  three  to  four  lobed  ovary  is  usually  elongated  antero- 
posteriorly.  The  uterus  as  in  other  members  of  this  genus  is  coiled  trans- 
versely between  the  crura  and  extends  from  the  level  of  the  ovarian  com- 
plex to  the  posterior  end  of  the  cirrus  pouch  at  the  beginning  of  the  second 
body  third.  The  vitelline  glands  occupy  an  extracecal  position  and  extend 
from  the  testes  to  the  middle  region  of  the  uterine  coils  which  is  found  in 
the  caudal  portion  of  the  second  body  third.  Eggs  numerous,  medium 
thick  shelled,  20ju  in  length  and  approximately  twice  as  long  as  wide. 
They  possess  a  long  polar  filament  at  each  end. 

Habitat:  Intestine  Host:  Fiber  zibethicus 

Locality:  Wray,  Colorado  Collector:  C.  H.  Gable 

Date:  October  30,  1916  No.  21.91  Ward  collection 

NUDOCOTYLINAE  Barker  1919 

Small  cup  shaped  Notocotylidae  with  thick  bodies,  without  ventral 
glands.  Genital  pores  separate,  ventral,  lateral,  in  posterior  half  of  body. 
Cirrus  pouch  pear-shaped,  enclosing  small  portion  of  seminal  vesicle. 
Vitelline  glands  strongly  developed  compact  masses,  lateral  to  ceca  and 
anterior  to  testes.  Uterus  in  transverse  folds,  in  anterior  half  of  body, 
extending  laterally  over  intestinal  crura. 

Type  genus:  Nudocotyle  Barker  1916 

Barker  would  include  Barisomum  Linton  1910  in  this  sub-family. 
This  is  a  doubtful  decision  since  in  the  genus  Barisomum  the  genital  pore 
is  in  the  anterior  body  third  and  the  shell  gland  lies  posterior  to  the  ovary. 
It  possesses  in  fact  certain  Notocotylid  characters  but  conforms  more  close- 
ly to  the  Pronocephalidae  than  to  the  Notocotylidae  in  the  position  of  the 
genital  pore,  and  the  character  and  position  of  the  genital  glands. 

NUDOCOTYLE  NOVICIA  Barker  1916 

Small  thick  oval  worms,  709  to  899/x  in  length;  500  to  657ju  in  breadth. 
Anterior  end  tapering  gradually,  posterior  markedly  truncate.  Dorsal 
surface  strongly  convex,  ventral  concave.  Body  smooth,  devoid  of  ventral 
papillae  or  spines.  Oral  sucker  sub  terminal,  spherical  50  to  65 /x  in  diame- 
ter; pharynx  wanting;  intestinal  ceca  undulating  but  without  diverticula. 
Male  and  female  genital  pores  separate,  ventral,  lateral,  in  beginning  of 
posterior  body  third.  Cirrus  pouch  large,  club-shaped,  about  one- third  of 
body  width  in  length.  It  lies  transversely  and  median  in  anterior  portion 
of  posterior  body  half.  Cirrus  without  spines.  Testes  extracecal  in  posi- 
tion, lying  in  same  level  in  posterior  fifth  of  body,  frequently  2  to  5  lobed. 
Ovary  elongated,  convoluted  or  lobed,  in  extreme  posterior  end  of  body 
between  testes  and  separated  from  them  by  intestinal  crura.  Shell  gland 


275]  NORTH  AMERICAN  MONOSTOMES  57 

compact,  anterior  to  ovary.  Laurer's  canal  and  receptaculum  seminis 
were  not  observed  by  Barker.  Eggs  oval,  twice  as  long  as  wide,  20  to  24/x 
long  10  to  13/i  wide.  With  long  polar  filament  on  each  end  about  five 
times  as  long  as  egg  itself. 

HERONIMIDAE  Ward  1917 

This  family  was  created  by  Ward  (1917)  to  hold  the  two  aberrant  genera 
Heronimus  MacCallum  (1902)  and  Aorchis  Barker  and  Parsons  (1914). 
Ward  called  attention  to  the  close  resemblance  of  the  two  forms  and 
suggested  that  they  might  prove  to  be  identical.  He  characterized  the 
family  as  follows:  "Moderate  sized  monostomes  with  thick,  elongate, 
soft  body,  slightly  flattened,  tapering  toward  both  ends.  Oral  sucker  weak; 
pharynx  large;  esophagus  short  or  absent;  ceca  simple,  narrow,  extending 
to  posterior  tip  but  not  united.  Vitellaria  compact,  tubular.  Uterus  with 
four  longitudinal  regions;  genital  pore  ventral  to  oral  sucker,  near  anterior 
tip.  Testis  tubular,  small;  copulatory  apparatus  poorly  developed.  In 
lungs  of  turtles,  northern  North  America." 

One  year  later  (1918)  the  same  author  restated  the  family  diagnosis 
with  the  following  addition:  " Vitellaria  compact  tubular,  shaped  like  an 
inverted  V.  Testes  tubular,  lobed  or  with  short  branches,  united  into  a 
V-shaped  organ  with  the  apex  anteriad,"  and  again  stated  that  the  two 
forms  probably  belonged  to  the  same  genus.  About  a  year  later  Stunkard 
(1919)  presented  a  paper  in  which  he  showed  that  the  apparent  difference 
in  the  two  forms  was  due  largely  to  the  partially  diagrammatic  figure  of 
MacCallum  (1902)  and  to  the  discrepancies  in  the  description  of  Barker 
and  Parsons  (1914)  and  that  the  two  forms  are  identical,  thus  not  only 
belonging  to  the  same  genus  as  suggested  by  Ward  but  representing  a 
single  species,  Heronimus  chelydrae  MacCallum. 

HERONIMUS  CHELYDRAE  W.  G.  MacCallum  1902 

Syn:  Aorchis  extensus  Barker  and  Parsons  1914 
Aorchis  extensus  Ward  1917 
Monostoma  sp.  Stiles  and  Hassall  1894 

The  genus  was  created  by  MacCallum  (1902)  to  include  worms  collected 
from  the  lungs  and  bronchi  of  Chelydra  serpentina.  The  genus  stands 
according  to  MacCallum  "in  many  respects  far  apart  from  the  other 
genera,"  especially  in  the  position  and  nature  of  the  genital  opening,  in  the 
complicated  structure  and  course  of  the  uterine  tract,  in  the  unusual 
formation  of  the  yolk  glands,  in  the  presence  of  but  one  testicle  and  in  the 
position  of  the  excretory  pore.  The  genus  may  be  recognized  by  the 
following  diagnosis:  Medium  to  large  monostomes  with  semicyclidrical 
body  tapering  slightly  towards  both  ends;  strongly  muscular.  Mouth 


58  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [276 

opening  terminal,  oral  sucker  small,  pharynx  weak  but  distinct.  Esophagus 
very  short;  intestinal  ceca  simple,  ending  blindly  in  the  extreme  posterior 
of  the  body.  Genital  pore  inconspicuous,  median,  ventral  to  the  pharynx. 
Ovary  situated  in  the  anterior  one-fourth  of  the  body,  lateral,  usually 
intracecal;  shell  gland  smaller  than  the  ovary  and  posterior  to  that  organ. 
Receptaculum  seminis  present,  usually  about  two-thirds  as  large  as  the 
ovary.  Laurer's  canal  absent.  Uterus,  except  for  the  four  longitudinal 
loops,  coiled  around  the  intestinal  crura  from  the  level  of  the  ovary  to  the 
posterior  end  of  the  animal.  Vitelline  gland  a  coarse,  compact  U-shaped, 
closed  tubular  structure,  dorsal  to  the  intestine.  Testis  U-shaped,  closed 
portion  cephalad,  about  one-fourth  the  body  length  from  the  anterior 
end.  The  tubular,  irregularly  lobed  testicular  mass  extends  caudad  to  a 
level  about  one-eight  the  body  length  from  the  posterior  end.  Protrusible, 
non-muscular  cirrus  present.  Excretory  pore  median,  anterior,  dorsal  to 
the  pharynx.  Eggs  large,  ovoid,  thin  shelled,  containing  fully  developed 
miracidia  in  the  metraterm. 

The  anatomy  of  this  form  is  well  described  by  MacCallum  (1902)  and 
Barker  and  Parsons  (1914,  1917),  and  with  the  additions  and  corrections 
of  Stunkard  (1919)  calls  for  no  further  anatomical  discussion  here. 

The  writer  has  been  given  an  opportunity  to  examine  the  type  specimen 
of  this  species  deposited  in  the  United  States  National  Museum  and  can 
verify  the  statements  of  Stunkard  on  the  specific  identity  of  the  two  species. 

MacCallum  reported  the  original  material  from  Chelydra  serpentina 
taken  in  the  Grand  river  at  Dunville,  Ontario,  Canada.  Barker  and 
Parsons  (1914)  report  from  Chrysemys  marginata  taken  in  Lake  Emily, 
Minnesota,  and  the  Mississippi  river  and  later  (1917)  in  the  same  host 
taken  in  the  Mississippi  river  near  Fairport,  Iowa.  At  this  time  they  call 
attention  to  the  distribution  in  Illinois. 

Ward  (1917)  reports  this  species  from  " various  turtles"  taken  in  Michi- 
gan, Indiana,  Illinois  and  Nebraska.  Stunkard  (1919)  collected  this  species 
from  Chelydra  serpentina  taken  in  Illinois,  Ohio,  North  Carolina  and  Texas; 
in  Chrysemys  marginata  taken  in  Iowa,  Illinois,  Missouri  and  Kentucky; 
in  Pseudemys  elegans  and  Malacoclemmys  geographicus  in  Illinois;  Aro- 
mochelys  odoratus  and  Kinosternum  pennsyhanicum  in  North  Carolina. 
The  specimen  listed  by  Stiles  and  Hassall  (1894:253)  as  "Monostomasp.— 
Chelonia  gen.  sp.  (bronchi) — Illinois-Forbes-Leidy"  belongs  here. 

The  writer  has  found  this  species  in  Chelydra  serpentina  and  Chrysemys 
marginata  taken  in  the  drainage  ditch  at  Urbana,  Illinois;  in  Chrysemys 
marginata  taken  in  the  Mississippi  river  near  Fairport,  Iowa;  in  Graptemys 
geographicus  taken  near  Chicago,  Illinois;  in  Chelydra  serpentina  and 
Chrysemys  marginata  taken  in  Minnesota  and  in  Kinosternum  pennsylvani- 
cum,  Kinosternon  odoratus,  and  Chrysemys  pida,  a  new  host,  taken  in  North 
Carolina. 


277]  NORTH  AMERICAN  MONOSTOMES  59 

While  this  species  was  reported  by  MacCallum  as  "not  by  any  means  a 
constant  parasite,"  he  having  found  it  in  only  one  host  infected  of  a  number 
examined,  more  recent  data  show  this  worm  to  be  rather  constantly  present. 
In  seven  specimens  of  Chrysemys  marginata  collected  in  the  summer  of  1911 
from  Lake  Emily,  Minn.,  Barker  and  Parsons  found  five  infected,  one  of 
them  yielding  thirteen  worms  from  both  lungs.  The  same  authors  (1917) 
found  that  female  turtles  were  more  than  three  times  as  heavily  infected 
as  males,  Stunkard  (1919)  from  the  examination  of  "about  three  hundred 
turtles"  reports  the  heaviest  infection  in  one  host  as  six.  On  an  examina- 
tion of  "more  than  fifty  turtles"  he  found  no  difference  in  the  relative  in- 
fections of  males  and  females.  The  writer  has  examined  one  hundred  and 
two  hosts  of  six  different  species  and  of  these  forty-four  showed  infection 
with  these  worms.  The  highest  percentage  of  infection  for  any  species  was 
found  in  Cinosternum  pennsyhanicum  from  North  Carolina  in  which  34 
out  of  45  specimens  or  approximately  75  percent  were  infected.  The  highest 
number  of  individuals  from  a  single  host  of  this  species  was  eleven  while  a 
single  individual  of  Graptemys  geographicus,  and  the  only  one  of  eighteen 
which  showed  infection,  carried  twelve  worms  in  both  lungs. 

During  the  past  four  years  the  writer  has  had  opportunity  to  examine 
more  than  one-hundred  turtles  as  stated  above.  It  was  noted  early  in  the 
investigation  that  the  collections  made  in  different  seasons  showed  no 
striking  difference  in  percentage  of  infection.  It  was  then  undertaken  to 
determine  if  possible  the  length  of  life  of  this  parasite  in  the  definite  host. 
It  is  generally  understood  that  most  intestinal  paraties  have  an  annual 
cycle  and  depend  on  this  for  continuity  of  the  species.  However,  data  on 
this  point  seems  lacking  in  this  group.  The  work  on  Heronimus  chelydrae 
consisted  in  the  examination  of  a  number  of  turtles  collected  in  the  same 
region,  Raleigh,  North  Carolina,  at  various  seasons  of  the  year. 

Some  of  these  dissected  on  arrival  showed  relatively  heavy  infections, 
others  which  were  kept  in  the  laboratory  aquaria  for  periods  of  six,  twelve 
and  eighteen  months  still  carried  infection,  and  a  single  specimen  of  Chely- 
dra  serpentina  which  had  been  kept  in  an  aquarium  for  more  than  three 
years  yielded  two  specimens  of  Heronimus  chelydrae  and  a  single  nematode, 
probably  Camallanus  americanus.  As  was  stated  above  hosts  examined 
when  taken,  usually  carry  intestinal  forms  in  addition  to  the  lung  fluke 
already  mentioned,  while  those  which  have  been  kept  in  aquaria  for  a 
period  of  six  months  or  more  show  a  marked  reduction  in  the  number  of 
the  intestinal  forms.  There  is  no  apparent  change  in  the  number  of  the  lung 
flukes  present. 

Little  is  known  regarding  the  condition  of  parasites  during  hibernation 
of  the  host.  Blanchard  (1903)  records  that  hibernating  marmots  do  not 
contain  any  intestinal  parasites.  Ward  (1909)  reports  observations  carried 
out  on  the  frog,  Rana  mrescens.  In  this  he  says  that  parasitic  infection 
increases  steadily  up  to  hibernation,  and  does  not  decrease  during  the  latter 


60  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [278 

period;  that  the  parasites  reach  the  climax  of  sexual  maturity  soon  after 
the  host  emerges  from  the  winter  quarters.  They  discharge  their  eggs 
and  pass  out  from  the  body  of  the  host  soon  after  the  time  of  spawning, 
and  at  the  close  of  this  period  the  hosts  are  relatively  free  from  infection. 

Observations  of  the  writer  verify  the  sexual  inactivity  of  the  parasite 
Heronimus  chelydrae  during  the  early  part  of  the  winter  and  the  copious 
discharge  of  mature  miracidia  in  early  spring.  On  the  other  hand  these 
turtles  did  not  become  free  from  infection  at  any  time  during  the  period 
of  the  experiment.  It  must  be  kept  in  mind  however  that  the  turtles  used 
were  not  subject  to  natural  conditions,  i.e.,  no  opportunity  was  afforded 
for  hibernation  and  no  eggs  were  deposited  during  this  time.  That  trema- 
todes  adapted  to  partially  closed  cavities  can  live  longer  than  for  a  single 
reproductive  phase  is  evident,  since  in  the  instance  reported  above  in  which 
the  host  has  been  kept  for  a  period  of  more  than  three  years,  the  two  para- 
sites found  were  sexually  mature,  and  were  producing  large  quantities  of 
ripe  eggs  when  the  host  was  examined;  this  is  true  also  in  one  other  case 
in  which  the  host  was  kept  for  more  than  eighteen  months. 

COLLYRICLIDAE  Ward  1917 

This  family  was  created  to  hold  the  genus  Collyriclum  of  Kossack  and 
is  circumscribed  by  Ward  as  follows: 

"Small  to  moderate  sized  monostomes  with  discoidal  compressed,  not 
muscular  body,  broader  than  long.  Oral  sucker  weak;  pharynx  present; 
ceca  simple,  long,  capacious,  not  united.  Genital  pore  ventral  near  center 
of  body.  Vitellaria  follicular,  scanty,  antero-lateral;  ovary  much  lobed, 
symmetrical.  Uterus  posterior,  in  irregular  coils  which  show  an  antero- 
posterior  tendency,  terminal  region  enlarged.  Testes  oval,  symmetrical, 
behind  ovary.  Eggs  very  small.  Adults  parasitic  in  dermal  cysts  on  abdo- 
minal surface  of  the  skin  of  birds." 

In  the  light  of  our  present  knowledge  of  these  forms  the  family  diagnosis 
must  be  modified  with  respect  to  the  condition  of  the  testes.  Tyzzer  (1918) 
has  shown  the  testes  of  the  American  species  to  be  irregularly  lobed  and 
not  oval  as  described  for  the  European  species,  Collyriclum  faba  by  both 
Kossack  (1911)  and  Jegen  (1917).  The  writer  has  examined  a  number  of 
specimens  of  Collyriclum  colei  Ward  and  has  found  the  observation  of 
Tyzzer  stated  above  to  be  correct. 

Type  and  only  genus:  Collyriclum  Kossack  1911. 

American  representative:  Collyriclum  colei  Ward  1917 

COLLYRICLUM  COLEI  Ward  1917 
Syn:  M onostoma  faba  Cole  1911 

Collyriclum  faba  Tyzzer  1918 

Diagnosis:  Small  hemispherical  worms,  4  to  5  mm  in  length  and  breadth 
by  3  mm  thick.  Cuticula  covered  with  spines  35 /z  in  length,  arranged  in 
groups  which  form  rather  regular  rows  around  the  worm.  Mouth  terminal 


279]  NORTH  AMERICAN  MONOSTOMES  61 

or  slightly  dorsally  placed,  surrounded  by  a  muscular  sucker  220 /x  long  by 
375/z  wide.  Pharynx  smaller  140ju  long  by  125/i  wide,  adjacent  to  the 
sucker,  followed  by  short  esophagus  which  bifurcates  to  form  the  large 
voluminous  simple  intestinal  crura;  these  end  blindly  at  the  end  of  the 
middle  body  third.  Genital  orifice  ventral,  near  center  of  body.  Testes 
near  the  ends  of  the  crura,  lobed,  the  main  portion  pear-shaped.  Ovary 
in  intestinal  bifurcation,  three  branched,  each  division  containing  from  5 
to  10  lobes.  Vitellaria  well  developed,  imperfectly  symmetrical  with  5  to 
7  groups  on  the  left  and  7  to  9  on  the  right.  Uterus  much  coiled,  generally 
in  the  posterior  half  showing  a  tendency  to  antero-posterior  coiling.  Eggs 
small,  19  to  22  n  long  by  10  to  12/x  wide,  containing  in  the  end  portion  of 
the  uterus  a  fully  formed  miracidium. 

The  anatomy  of  these  worms  has  been  so  thoroughly  discussed  by  Tyz- 
zer  (1918)  for  the  American  species,  and  by  Kossack  (1911)  and  Jegen 
(1917)  for  the  European  species  that  it  does  not  seem  necessary  to  enter 
into  a  detailed  discussion  here.  I  desire  instead  to  give  a  comparison  of  the 
two  forms  since  Tyzzer  found  reason  based  largely  on  the  inconsistency 
of  Kossack's  description  and  figures  to  declare  the  American  material 
identical  with  that  found  in  Europe. 

Ward  (1917)  after  examination  of  the  material  reported  by  Cole  (1911) 
as  Monostoma  faba  pointed  out  distinct  differences  between  this  and  the 
European  form  described  by  Kossack  (1911).  The  following  is  his  state- 
ment, "As  a  cause  of  an  epidemic  among  sparrows  at  Madison  Wisconsin, 
Cole  (1911)  reported  under  the  name  of  Monostoma  faba  a  trematode  that 
in  reality  differs  distinctly  from  the  European  species.  The  form  of  the 
ovary,  the  extent  of  the  vitellaria,  the  dermal  spines,  and  other  details  of 
structure  disagree  with  the  recent  description  of  Kossack  who,  moreover, 
assigned  Rudolphi's  species."  [erroneously  attributed  to  Rudolphi,  really 
Bremser  (1831)  ]  "to  his  new  genus  Collyriclum.  The  American  form 
constitutes  a  new  species  in  this  genus  and  to  it  the  name  Collyriclum  colei 
may  be  given." 

One  year  later  (1918)  the  same  author  restated  the  differences  in  the 
two  species  as  follows:  "These  specimens  differ  clearly  from  the  European 
form  in  numerous  minor  details,  such  as  ovary,  yolk  glands,  dermal  spines, 
etc.,  and  demand  recognition  as  a  distinct  species  under  the  name  given 
here." 

Tyzzer  (1918)  made  a  comparison  of  the  two  forms  based  on  Kossack's 
description  of  Collyriclum  faba  and  concluded  that  the  two  species  were 
identical  despite  certain  distinct  differences  which  he  explained  away  on  the 
basis  of  the  discrepancies  between  Kossack's  description  and  figures.  The 
work  of  Jegen  (1917)  which  reached  America  after  Tyzzer's  had  appeared 
verifies  in  a  large  measure  the  description  of  Kossack  and  leaves  little 
doubt  that  the  American  material  is  distinct  from  Collyriclum  faba.  The 
following  is  the  diagnosis  of  this  species  as  given  by  Jegen:  "In  Cysten 


62 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[280 


Table  I.    Comparison  of  Collyriclum  faba  with  C.  colei 
After  Tyzzer,  1918,  with  additions  from  Jegen,  1917 


European  Material 
Collyriclum  faba 

American  Material 
Collyriclum  colei 

Shape 

Somewhat  hemispherical. 

The  same.  Minor  additional 
points  noted. 

Size 

4.2-4.8X4.5-5.46  mm 
Jegen  from  P.  domesticus 
4.4-5.2X6-5.4. 

4.  1X4.  8X2.  9  mm. 

Mouth 

Ventrally  placed. 

Dorsal  to  margin  of  body.  In 
flattened  specimens  appears 
ventral  from  over-riding  of 
larger  dorsal  surface. 

Uterus 

Similarly  arranged  in  both. 

Intestine 

Identical  in  form. 

and  extent. 

Vitellaria 

Symmetrical,  each  with 
seven  rarely  six  or  eight, 
follicle  groups. 

Not  perfectly  symmetrical,  five 
to  seven  on  left  and  seven  to 
nine  follicle  groups  on  right 
side. 

Ovary 

T-shaped,  each  of  three  divisions 
with  four  or  five  branches. 
Jegen  reports  5-7  lobes. 

Of  similar  form,  each  division 
from  5-10  lobes. 

Testes 

Oblong  or  saber-shaped. 

Showing  three  or  more  large 
processes  and  other  minor 
irregularities,  and  curved  over 
the  blind  ends  of  the  intestine. 
In  gross  specimens  seen  only 
in  part,  appearing  oblong  or 
saber  shaped.  Measurement 
not  feasible. 

Genital  orifices 

General  agreement  in  both. 

Oral  sucker 

0.204,5  to  .441,  2mm. 
Jegen,  0.3  to  0  .  45  mm. 

Average,  0.219,8X0.  375,3  mm. 

Pharynx 

0.129,1  to  0.193,7  mm. 
Jegen,  0.113  to  .145  mm. 

Average  0.  140  X  .  124,5  mm. 

Spines 

"Arranged  in  lines,  with  the  in- 
dividual    spines     apparently 
widely  separated  from  one  an- 
other."  Up  to  35  n  in  length. 

Jegen:  in  groups  of  4  to  8, 
28  to  35M. 

Set  in  annular  rugae;  maximum 
distance  separating  latter,  .45 
to  53/i.  Up  to  35,5/i  in 
length.  Average  dorsal,  27,9/j, 
long. 

Ova 

19,8X9,7/x. 

19  to  21,4X10,6-11,6^. 
Average  20,5X11,3/*. 

281]  NORTH  AMERICAN  MONOSTOMES  63 

zu  zweien  vorkommende  Trematoden.  Korperform  annahernd  rund. 
Dorsale  Flache  stark  gewolbt,  ventrale  weniger  gewolbt  bis  flach.  Haut 
mit  Stacheln  besetzt,  die  in  Gruppen  von  vier  bis  acht  Einzelstacheln 
stehen.  Mundsaugnapf  endstandig.  Darmschenkel  einfach  und  zwei 
Drittel  der  Breite  des  Korpers  einnehmend.  Bauchsaugnapf  fehlt.  Ter- 
minal am  Hinterende  eine  muskelreiche  Partie,  die  bei  der  Fortbewegung 
als  Saugorgan  Wirkt.  Genital  pori  auf  einer  papillenartigen  Erhohung, 
median  etwas  vor  der  Korpermitte  gelegen.  Excretionsblase  birnformig 
und  bedeutend  iiber  die  Mitte  hinausreichend.  Dotterstocke  aus  zwei 
seitlich  gelegenen  Follikelgruppen  (7)  bestehend.  Hoden  dorsal,  den 
Darmschenkelspitzen  genahert.  Keimstock  vor  den  Hoden,  im  ersten 
Korperdrittel,  aus  drei  lobosen  Gruppen  bestehend.  Schalendriise  unmit- 
telbar  neben  und  unter  dem  Keimstock.  Laurersche  Kanal  vorhanden. 
Receptaculum  seminis  fehlt.  Uterusschlingen  hauptsachlich  im  hinteren 
Korperteil.  Eier  ohne  Filamente,  mit  scharf  abgesetztem  Deckel  und 
einer  kleinen,  seitlichen  Spitze  am  entgegengesetzten  Pol,  sehr  zahlreich." 

Because  of  the  distinct  differences  shown  by  Tyzzer  his  table  is  incor- 
porated with  Jegen's  corrections  to  Kossack's  description  of  Collyriclum 
faba.  It  is  printed  on  preceding  page  of  this  paper. 

A  study  of  the  table  shows  clearly  that  the  species  in  question  differ 
with  respect  to  the  asymmetry  and  extent  of  the  vitellaria  and  the  form 
of  the  testes.  In  regard  to  the  agreement  of  the  American  material  with 
Kossack's  description  Tyzzer  says:  "that  the  American  material  agrees 
very  closely  in  most  respects  with  Kossack's  description,  there  being 
similarity  of  size  and  shape,  in  the  appearance  of  the  alimentary  canal  and 
uterus,  and  in  the  po'sition  of  the  genital  orifices.  The  measurements  of  the 
oral  sucker,  pharynx,  esophagus,  spines,  and  ova  correspond  rather  closely, 
and  such  differences  as  occur  appear  to  be  within  the  limits  of  species 
variation." 

Regarding  the  grouping  of  the  spines  Kossack  (1911:574)  "Die  Haut 
ist  mit  Stacheln  bedeckt,  die  in  regelmassigen  Reihen  angeordnet  sind. 
Die  einzelnen  Stacheln  sind  ziemlich  weit  voneinander  entfernt  und 
durchschnittlich  0.035  mm  lang."  Jegen  describes  the  spines  as  being 
arranged  in  groups  in  rows.  Four  to  eight  spines  in  a  group,  and  says, 
"Kossack  erwahnt  (S.  574)  dass  die  Stacheln  in  regelmassigen  Reihen  ange- 
ordnet seien.  Ich  glaube  nun  nicht,  wie  Odhner  dies  ausspricht,  dass  er 
die  Stachelgruppen  iibersehen  hatte,  wenn  sie  iiberhaupt  in  seinem  Mate- 
rial vorhanden  waren.  Vielmehr  liegt  die  Moglichkeit  vor,  dass  er  ein 
Entwicklungsstadium  vor  sich  hatte,  bei  dem  die  Gruppen  noch  nicht 
vollstandig  gebildet  waren." 

Tyzzer  calls  attention  to  the  ovary  which  he  says  "presents  more 
lobules  than  was  noted  by  Kossack."  Jegen  states  that  the  ovary  is  very 
strongly  lobed  and  found:  "An  jedem  der  drei  Aste  sitzen  fiinf  bis  sieben 


64  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [282 

soldier  einzelner  Knollen."  Tyzzer  states  further  that  "the  basis  for  differ- 
entiation of  an  American  species  at  the  present  time  appears  therefore  to 
be  rather  inadequate."  That  he  is  dealing  with  the  same  species  as  that 
reported  by  Cole  (1911)  and  later  named  Collyridum  colei  by  Ward  (1917) 
cannot  be  doubted  and  according  to  his  statement  his  material  "is  un- 
doubtedly of  the  same  species." 

Although  Tyzzer  failed  to  find  any  difference  which  would  warrant  a 
second  species  of  Collyriclum  the  present  investigation  has  shown  that 
except  in  minor  detail  the  work  of  Jegen  agrees  with  that  of  Kossack,  and 
on  the  basis  of  the  descriptions  of  these  investigators  the  American  mate- 
rial is  distinct  from  Collyriclum  faba  in  that  the  testes  are  lobed  and  in  the 
asymmetry  and  extent  of  development  of  the  vitellaria.  It  is  impossible 
to  explain  away  these  differences  either  as  "artefacts  in  preservation"  or 
as  "individual  variation,"  nor  is  it  probable  that  both  Kossack  and  Jegen 
have  overlooked  these  features.  On  the  basis  of  these  difference  the  Amer- 
ican material  must  be  recognized  as  a  distinct  species  under  the  name  Colly- 
riclum colei  Ward. 

A  preliminary  study  of  specimens  of  Collyriclum  faba  secured  by  Pro- 
fessor Ward  bears  out  the  description  of  Kossack  and  Jegen  as  well  as  the 
conclusions  of  the  writer  drawn  from  the  study  of  their  papers  and  compari- 
son with  American  specimens  of  this  genus.  A  more  thorough  study  of  the 
European  material  is  not  feasible  at  this  time  but  is  anticipated  at  an 
early  opportunity. 

REMARKS  ON  THE  LIFE  HISTORY 

The  life  history  of  Collyriclum  faba  is  doubtfully  known.  Tyzzer  gives 
a  careful  description  of  the  development  of  the  egg  of  Collyriclum  colei 
from  the  time  of  fertilization  to  maturity  in  the  end  portion  of  the  uterus. 
Regarding  the  mature  eggs  he  says  "The  eggs  stored  in  the  terminal  por- 
tion of  the  uterus  evidently  contain  miracidia,  the  morphological  features 
of  which  are  not  clear  in  fixed  material  owing  to  imperfect  preservation 
and  shrinkage."  He  continues  with  a  description  of  the  "hair-like" 
structures  which  have  been  distinguished.  This  adds  evidence  that  a 
miracidium  is  present. 

The  work  of  Jegen  (1917)  which  is  an  attempt  at  the  life  history  of 
Collyriclum  faba  differs  radically  from  the  statements  of  Tyzzer  in  th?t  he 
finds  the  eggs  contain  two  embryos  which  are  not  miracidia  but  young 
trematodes;  these  need  only  to  be  incubated  in  the  intestine  of  the  host 
that  they  may  break  out  of  the  egg  shell  and  freed  with  the  excrement, 
may  wander  into  the  feather  follicle.  He  found  also  cysts  (Dauercyste) 
which  after  a  longer  period  of  incubation  break  open  and  the  worm  enters 
the  follicle  of  a  feather.  Jegen  summarizes  his  work  as  follows:  "Die 
Eier  von  Collyriclum  faba  werden  durch  den  Wirt  mit  dem  Parasiten  auf  ge- 


283]  NORTH  AMERICAN  MONOSTOMES  65 

pickt  und  gelangen  in  den  Vogeldarm,  wo  die  Embryonem  ausschliipfen. 
Mit  den  Excrementen  werden  letztere  ins  Freie  befordert,  wo  sie,  sofern 
die  Moglichkeit  zur  Infektion  vorhanden  ist,  direkt  in  die  Federfollikel 
der  jungen  Vogel  einwandern.  Im  andern  Fall  bilden  sich  Dauercysten, 
die  nach  langerer  Entwicklungsruhe  such  auflosen  und  den  eingeschlos- 
senen  Organismus  frei  lassen,  so  dass  er  ebenfalls  in  die  Federfollikel  ein- 
wandern kann."  This  summary  of  Jegen  is  supported  by  experimental 
evidence  gained  by  incubation  of  the  eggs  in  a  portion  of  the  intestine  of 
an  infected  bird  as  well  as  by  numerous  attempts  to  incubate  the  eggs 
which  had  not  passed  through  the  intestine  of  the  host  altho  he  says  these 
gave  negative  results.  The  "Dauercysten"  he  found  in  excrement  of  infec- 
ted birds,  which  was  dried  by  exposure  to  air,  and  at  other  times  in  the 
nest  and  on  the  feathers  of  young  sparrows. 

The  outline  of  Jegen  gives  essentially  a  direct  development  which 
omits  the  parthenogenetic  stages  observed  in  all  cases  where  the  life 
history  of  digenetic  trematodes  is  known.  Observations  of  the  writer 
support  the  view  of  Tyzzer  that  a  miracidium  is  present  in  the  mature  egg 
in  the  uterine  egg  sac.  The  fully  developed  miracidium  shows  well  devel- 
oped germ  balls.  This  is  in  direct  contrast  to  the  findings  of  Jegen  who 
says  that  the  embryo  contains  two  well  developed  germ  balls  with  numer- 
ous others  which  disappear  later  in  course  of  development.  Jegen  found 
that  the  eggs  would  develop  only  in  the  intestine  of  the  host  and  when  fed 
to  uninfected  birds  empty  egg  shells  and  embryos  were  found  on  the  second 
and  third  day.  He  neither  states  nor  demonstrates  that  these  experimental 
birds  became  infected  with  the  adult  parasites. 

The  work  of  Jegen  dealing  with  the  life  history  of  Collyriclum  is  full 
of  gaps.  The  life  history  as  given  is  bridged  over  by  supposition.  The 
infection  of  the  sparrows  by  feeding  of  eggs  is  not  demonstrated,  only 
the  presence  of  embryos  which  may  well  be  miracidia.  Jegen  does  not 
demonstrate  beyond  doubt  that  these  cause  the  formation  of  the  cysts  in 
the  sparrow.  The  "Dauercysten"  which  he  says  infect  directly  the  host 
based  on  his  experiment  of  the  dried  excrement  certainly  serve  to  protect 
the  parasite  from  dessication  until  it  can  reach  the  intermediate  host; 
nothing  indicates  whether  this  be  a  miracidium  or  another  infective  stage; 
and  the  periodicity  of  occurrence  of  the  adult  parasite  in  correlation  with 
a  rainy  season  tends  to  show  that  the  former  is  the  correct  interpretation. 

The  work  of  Jegen  is  apparently  a  misinterpretation  of  the  life  history 
and  leaves  much  to  be  done  in  order  to  demonstrate  the  facts.  The  only 
clear  contribution  of  this  author  to  the  life  history  of  this  form  lies  in  the 
discovery  of  the  "Dauercysten"  which  he  apparently  misinterpreted. 
Many  more  extensive  and  careful  experiments  must  be  carried  out  in  order 
to  demonstrate  conclusively  the  complete  life  history  of  this  form. 


66  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [284 

Species  Inquirendae 
CLINOSTOMUM  (?)  INCOMMODUM  (Leidy) 

Syn:  Monostomum  incommodum  Leidy  1856 
Distoma  oricola  Leidy  1884 
Distomum  incommodum  Leidy  1890 
Monostomum  incommodum  Leidy  1904 

Monostomum  incommodum  is  described  by  Leidy  as  follows:  "Body 
compressed,  above  convex,  below  concave,  sides  parallel  anteriorly  convex, 
posteriorly  angularly  convex.  Head  continuous  with  the  body,  obliquely 
truncated.  Mouth  round,  surrounded  with  a  wide  circular  lip  which  is 
emarginate  below.  Male  generative  aperature?  communicating  with  a 
hemispherical  cavity  (acetabulum?)  one-fourth  the  length  of  the  body  from 
the  head.  Length  9  lines,  breadth  lJ/£  lines. 

Habitat:  Fauces  Host:  Alligator  mississippiensis 

Locality:  Florida  Collector:  J.  W.  Bailey 

Date:  Previous  to  1856 

Leidy  (1890)  places  this  species  as  Distomum  incommodum  and  as  a 
synonym  of  this  species  his  Distoma  oricola  from  the  mouth  of  Alligator 
mississippiensis.  On  the  basis  of  the  later  determination  of  Leidy  (1890) 
his  description  of  Distoma  oricola  is  here  included  for  the  purpose  of  com- 
parison and  as  evidence  for  the  disposition  of  Monostomum  incommodum. 

Distoma  oricola  Leidy  1884 

"Body  elongated  elliptical,  moderately  wider  and  thicker  posteriorly  and 
ending  in  a  blunt,  angular  extremity,  convex  dorsally  and  flat  ventrally, 
unarmed,  smooth  or  minutely  wrinkled  transversely.  Mouth  subterminal, 
and  enclosed  with  a  reniform  lip  succeeded  by  a  linear  annulus.  Acetabu- 
lum large,  globular,  included  at  the  anterior  fourth  of  the  body,  and  open- 
ing ventrally  by  a  conspicuous  central  aperature.  Generative  orifice 
ventral,  at  the  posterior  fourth  of  the  body.  Length,  15  to  20  mm;  breadth, 
3  mm.  Eight  specimens  obtained  from  the  mouth  of  the  alligator,  A. 
mississippiensis,  in  Florida,  by  Mr.  Stuart  Wood." 

Pratt  (1902)  surmises  that  this  species  is  allied  to  the  genus  Clinosto- 
mum.  This  view  is  supported  by  Ward  (1918).  Then  if,  according  to  this 
view  the  determination  of  Leidy,  that  Distoma  oricola  is  a  synonym  of 
Monostomum  incommodum  which  he  determined  later  (1890)  as  a  Distome, 
Distomum  incommodum,  be  accepted,  Monostomum  incommodum  is  like- 
wise allied  to  the  genus  Clinostomum. 


285]  NORTH  AMERICAN  MONOSTOMES  67 

MONOSTOMUM  ORNATUM  Leidy  1856 
Syn. — Monostomum  ornatum  Brandes  1892 
Monostomum  ornatum  Braun  1893 
Monostomum  ornatum  Diesing  1858 
Monostomum  ornatum  Monticelli  1892 
Monostomum  ornatum  Stafford  1902 

This  species  was  described  by  Leidy  as  follows: 

"Body  slightly  compressed  ovoidal,  anteriorly  broad;  yellow  variegated 
with  brownish  red.  Mouth  infero-terminal,  acetabuliform,  transversely 
oval.  Penis  conical,  protruding  a  short  distance  below  the  mouth.  Female 
aperture  a  short  distance  below  the  penis.  Length  1  to  1J^  lines,  breadth 
}/2  to  %  line,  thickness  J4  to  J^  line." 

Habitat:  Body  cavity  Host:  Rana  pipiens 

Locality:  Philadelphia  Collector:  H.  W.  Warren 

Stafford  (1902)  questions  the  determination  of  these  worms  and  con- 
jectures that  they  belong  either  to  the  genus  Haematoloechus  sp.  which 
is  commonly  found  in  the  lungs  of  frogs  or  to  Dist.  quietum  or  Cephalogoni- 
mue  amer.  and  have  been  liberated  in  the  first  case  from  the  lung  and  in  the 
other  cases  from  the  small  intestine  of  the  host.  He  inclines  to  the  former 
view  uon  account  of  the  ease  with  which  the  small  ventral  sucker  may  be 
overlooked  and  the  readiness  with  which  worms  may  be  freed  from  the  lungs 
without  observation."  He  adds  that,  "it  is  unlikely  to  be  Distomum  quietum 
from  the  position  of  the  genital  openings"  and  that  "it  could  scarcely  have 
been  Dist.  retusum  (Ceph.  amer.?)  since  he  reports  it  also  in  the  same  paper 
although  he  does  not  describe  it  there  but  in  an  earlier  number." 

In  regard  to  the  habitat  of  Monostomum  ornatum  Stafford  says  that  "of 
the  hundreds  of  frogs  I  have  examined  I  have  never  yet  found  a  Trematode 
free  in  the  body  cavity  and  I  doubt  if  anybody  else  has  ever  obtained  one 
that  did  not  first  get  there  by  the  accidental  cutting  or  tearing  of  some 
other  organ." 

The  above  assumption  of  Stafford  that  trematodes  do  not  occur  free  in 
the  body  cavity  of  frogs  appears  to  be  doubtfully  correct.  Osborn  (1922) 
and  Cort  (1913)  report  encysted  Clinostomum  in  the  body  cavity.  The 
writer  in  examination  of  numbers  of  frogs  has  been  able  to  observe  these 
and  has  several  times  found  some  of  these  worms  out  of  their  cysts  and  free 
in  the  body  cavity.  These  frogs  were  opened  most  carefully  and  worms 
that  might  have  been  freed  by  the  cutting  of  the  body  wall  could  not 
have  found  their  way  to  remote  parts  of  the  cavity  in  the  time  consumed 
by  the  operation  and  examination.  On  the  other  hand  it  is  hardly  prob- 
able that  the  dozen  specimens  recorded  should  escape  from  the  lungs 
unnoticed  as  suspected  by  Stafford  and  none  be  left  to  show  the  normal 
habitat.  However,  as  Stafford  has  noted  and  as  was  stated  above,  the  worm 
could  scarcely  have  been  Distomum  retusum  (Cephalogonimus  americanus?) 


68  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [286 

since  it  is  recorded  in  the  same  paper.  Stafford,  however,  has  failed  to  note 
that  Leidy  recorded  also  in  this  same  paper  Distomum  variegatum  from  the 
lungs  of  Rana  pipiens  which  he  also  describes  in  the  same  "earlier  number" 
in  which  he  describes  Distomum  retusum.  Hence  Haematoloechus  is  ruled 
out  as  well.  From  the  habitat  of  these  worms  the  writer  suspects  that  it 
may  possibly  be  a  larval  stage  of  a  species  of  Clinostomum.  The  descrip- 
tion is  so  meager  that  it  is  impossible  to  place  it  in  any  definite  manner. 

MONOSTOMUM  SPATULATUM  Leidy  1858 
Syn:  Monostomum  spathulatum  Diesing  1859 

The  following  description  given  by  Leidy  includes  the  only  available 
data.  "Body  flat,  oblong  ovate,  narrowing  anteriorly,  obtuse  posteriorly, 
color  white,  with  brown  tortuous  lines  indicating  the  course  of  the  oviduct. 
Mouth  acetabuliform,  circular.  Testes  three,  alternating  on  each  side 
posteriorly  with  the  oviduct.  Ovaries  on  each  side  finely  lobulated. 
Generative  aperture  small  a  short  distance  behind  the  mouth.  Penis 
undistinguishable.  Length  3-4  lines:  breadth  J/£  line. 

Habitat:  Gall-bladder.  Host:  Fish  species  unknown 

Locality:  Eastern  U.  S.  Collector:  Jeffries  Wyman 

MONOSTOMUM  AFFINE  Leidy  1858 
Syn:  Notocotyle(?)affine  Barker  1916 

Leidy  described  this  species  as  follows:  "Body  spatulate  narrowest 
anteriorly,  flat;  posterior  end  obtuse,  with  an  excretory  orifice  communi- 
cating with  a  well  marked  canal  traceable  as  far  forward  as  the  commence- 
ment of  the  oviduct.  Mouth  round,  oral  acetabulum  small,  followed  by 
a  smaller  pharyngeal  bulb.  Intestine  simple,  traceable  on  each  side  to 
the  posterior  end  of  the  body.  Testes  four,  posterior  to  the  position  of  the 
distended  oviducts.  Ovaries  finely  lobulated,  situated  on  each  side  exter- 
nal to  the  position  of  the  intestine;  oviduct  transversely  tortuous  and  dis- 
tended with  brown  ova.  Penis  ensheathed,  long,  tortuous,  echinate. 
Generative  aperture  small,  acetabuliform.  Ova  oval  and  prolonged  at  one 
pole,  or  sub-pyriform.  Length  of  body  6J/2  lines;  breadth  1  line." 

"Four  specimens  were  obtained  by  Dr.  J.  N.  Corse  from  the  bile-ducts 
and  gall-bladder  of  the  muskrat  (Fiber  zibethicus).  Closely  allied  to  M. 
hippocrepis  Diesing,  but  has  no  trace  of  the  horse-shoe  like  collar  to  the 
head." 

As  is  stated  previously  in  this  work  the  suggestion  of  Barker  appears 
to  be  a  misfit  on  the  basis  of  the  pharynx,  the  echinate  penis  and  the 
undivided  excretory  canal  which  Leidy  says  is  traceable  as  far  forward  as 


287]  NORTH  AMERICAN  MONOSTOMES  69 

the  beginning  of  the  oviduct.  These  characters  are  fundamental  differences 
such  as  are  used  to  separate  families  and  groups  and  on  the  basis  of  these 
differences  the  supposition  of  Barker  (1916)  seems  untenable. 

MONOSTOMUM  ASPERUM  Vafflant  1863 
Syn:  Monostomulum  aspersum  Brandes  1892 

Monostomum  aspersum  Pratt  1902 

Vaillant  described  this  species  as  follows:  1.4  to  1.9  mm  long  by  0.94 
mm  wide,  elongated,  both  ends  rounded;  dorsal  surface  convex,  ventral 
flat ;  cuticula  in  the  anterior  %  densely  covered  with  small  spines  regularly 
spaced  and  arranged  in  alternating  rows.  Mouth  opening  round.  The 
digestive  system  composed  of  muscular  esophageal  bulb,  followed  by  a  long 
esophagus  which  extends  to  the  middle  of  the  body  where  it  bifurcates  to 
form  the  two  ceca  which  extend  to  the  level  of  the  excretory  bladder.  The 
excretory  bladder  forms  a  semi-oval  sac,  which  occupies  the  posterior  end  of 
the  animal.  The  genital  organs  are  between  the  excietory  bladder  and  the 
ends  of  the  intestinal  ceca.  The  male  organs  are  composed  of  a  curved 
spinous  penis,  with  a  testicle,  a  vesicula  seminalis  and  a  deferent  canal. 
The  female  organs  are  wanting  or  in  some  individuals  incompletely  devel- 
oped and  consist  only  of  a  granular  cell  mass. 

Found  in  transparent  sub-epidermal  cysts  of  Siren  lacertina. 

In  a  later  paper  the  same  author  (Vaillant,  1863a:347)  expresses  doubt 
in  regard  to  his  interpretation  of  the  sex  organs  which  he  says  appear  to 
be  only  poorly  developed. 

On  the  basis  of  the  descriptions  of  Vaillant,  Brandes  considered  this 
as  a  larval  form  but  attempted  no  further  indication  for  the  disposition 
of  the  species.  Monticelli  (1892)  enumerates  it  without  any  attempt  to 
determine  its  rightful  place.  Pratt  assigns  to  it  the  same  place  as  did 
Brandes. 

Both  accounts  of  this  worm  are  such  that  the  inference  may  be  readily 
drawn  regarding  its  larval  nature.  Neither  account  gives  evidence  of  any 
individual  in  a  sexually  mature  state.  The  sex  organs  are  poorly  developed 
and  no  mention  is  made  of  a  uterus  or  of  eggs  which  would  indicate  sexual 
maturity.  The  exceptional  habitat  assigned  to  this  worm  by  Vaillant  which 
he  says  is  comparable  to  that  of  Monostomum  faba  Bremser  is  not  so  rare 
in  the  light  of  the  present  knowledge  of  the  life  histories  of  distomes  and 
is  quite  in  contrast  to  what  is  now  known  of  the  monostome  life  history. 
Many  distomes  are  known  to  pass  a  portion  of  their  life  cycle  encysted  in 
the  skin  and  superficial  layers  of  the  body,  while  no  such  stage  has  yet  been 
found  in  the  cycle  of  a  monostome.  The  description  of  Vaillant  as  well  as 
his  figures  are  so  inadequate  that  it  would  be  hazardous  to  speculate  on  the 
systematic  position  of  this  form  more  than  to  say  on  the  basis  of  the  digestive 
system  the  cuticular  spines  and  what  has  been  given  regarding  the  genital 
glands  that  it  is  probably  the  immature  stage  of  a  distome. 


70  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [288 

MONOSTOMUM  AMIURI  Stafford  1900 

This  trematode  taken  from  the  swim  bladder  of  Amiurus  nebulosus  by 
Stafford,  is  described  by  him  as  follows:  "About  5  mm  long  and  2.25 
mm  broad  much  flattened  and  is  broadest  in  its  posterior  two-thirds,  the 
anterior  third  narrowing  towards  the  mouth-sucker.  The  living  animals 
are  very  soft  bodied,  inactive  creatures." 

"The  integument  bears  a  cuticle  and  is  apparently  very  thin  the  sub- 
cuticular  and  glandular  parts  seem  to  have  a  similar  structure  to  the  same 
parts  of  the  Distomes  with  which  I  am  most  acquainted.  The  intestinal 
system  begins  with  the  mouth  whose  thick  muscular  walls  form  the  oral 
sucker.  Following  this  is  a  muscular  pharynx  and  a  narrow  esophagus 
which  gives  rise  to  two  lateral  intestinal  ceca,  extending  as  broad  tubes  to 
near  the  posterior  end  of  the  body  where  they  end  blindly." 

"The  posterior  excretory  bladder  unpaired." 

"The  reproductive  system  is  of  the  usual  complex  type.  Each  individ- 
ual dioecious.  The  testes  are  situated  most  posterior  in  the  body,  between 
the  median  expulsion  tube  of  the  excretory  system  and  the  ends  of  the 
intestinal  ceca,  the  vasa  efferentia  rise  out  of  their  anterior  ends  and 
proceed,  by  a  direct  course,  to  near  the  middle  of  the  animal  where  they 
meet  in  the  vesicula  seminalis.  This  runs  forward  and  opens  by  a  muscular 
penis  on  the  ventral  surface  of  the  worm,  about  one-third  from  its  anterior 
end.  The  ovary  is  located  a  little  behind  the  middle  of  the  animal.  The 
uterus  filled  with  eggs  occupies  most  of  the  posterior  two-thirds  of  the  body 
and  opens  by  a  bulbous  vagina  immediately  behind  and  to  the  right  of  the 
penis.  The  two  lobular  yolk  glands  lie  outside  of  the  forked  intestine  and 
extend  from  the  level  of  the  genital  openings  to  the  hind  end  of  the  animal. 
A  longitudinal  yolk  duct  receives  the  yolk  cells  from  the  numerous  follicles 
on  each  side  and  conducts  them,  by  a  transverse  tube  in  the  region  of  the 
ovary,  to  a  yolk  reservoir  that  communicates  with  the  oviduct  close  by 
the  shell  gland.  The  egg  is  45  by  24ju  in  size  and  its  blunt  broader  end  is 
provided  with  a  short  hooked  filament." 

The  description  and  figure  of  Stafford  shows  a  remarkable  similarity 
to  the  Heterophyidae  with  which  the  worm  agrees  in  having  simple  sac- 
like  intestinal  ceca  extending  to  the  posterior  end,  genital  pore  in  immediate 
neighborhood  of  the  ventral  sucker  if  that  organ  is  what  has  been  inter- 
preted as  the  female  genital  opening  by  Stafford.  Testes  oval,  symmetri- 
cally arranged  near  the  posterior  end,  seminal  vesicle  S-shaped,  ovary  oval, 
median,  anterior  to  the  testes.  Vitellaria  lateral  to  the  intestinal  ceca; 
extending  from  the  level  of  the  testes.  The  eggs  also  fall  within  the  size 
found  in  this  family  but  differ  in  having  a  short  hooked  filament  at  the 
blunt  end.  It  differs  also  in  that  scales  have  not  been  recorded  for  this 
species  by  Stafford. 


289]  NORTH  AMERICAN  MONOSTOMES  71 

In  the  above  comparison  the  bulbous  vagina  of  Stafford  has  been  con- 
strued to  be  the  ventral  sucker  and  considering  this  as  a  sucker  this  species 
agrees  in  every  important  anatomical  feature  with  the  Heterophyidae.  The 
absence  of  scales  here  if  they  have  not  actually  been  overlooked  could  be 
considered  only  of  specific  import  and  according  to  the  findings  of  Ward 
and  Hirsh  (1915:148)  "spines  and  scales  are  caducous  in  life  and  are  easily 
lost  also  if  the  specimens  lie  in  preserving  fluid  for  some  time. 
^  The  fact  that  this  species  was  found  in  the  swim  bladder  of  Amiurus 
nebulosus  is  not  sufficient  reason  for  its  separation  from  the  Heterophyidae 
since  three  genera  of  that  family  are  known  to  have  larval  stages  in  fish, 
namely,  Metagonimus,  Cryptocotyle,  and  Paracoenogonimus.  Ransom 
(1920:530)  surmises  that  "Heterophyes,"  the  genus  to  which  Monostomum 
amiuri  seems  to  be  most  closely  related,  "occur  in  their  immature  stages  in 
fish,"  the  adults  thus  far  having  been  found  in  fish  eating  birds  and  mam- 
mals. 

Habitat:  Swim  bladder  Host:  Amiurus  nebulosus 

Locality:  probably  near  Toronto,       Collector:  Stafford 
Canada 


72  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [290 


THE  POLYPHYLETIC  ORIGIN  OF  THE  MONOSTOMES 

From  the  earliest  records  of  the  Monostomata  up  to  the  present  time 
this  group  of  parasites  has  served  for  a  dumping  ground  for  inaccurately 
studied  species  in  which  the  acetabulum  has  been  wrongly  interpreted  or 
overlooked  entirely.  Many  species  have  since  been  studied  more  carefully 
and  consequently  have  been  transferred  to  other  genera.  Out  of  this  has 
arisen  the  problem  of  the  origin  of  the  Monostomata.  Accumulative 
evidence  has  lead  to  the  belief  that  these  forms  are  directly  related  to  var- 
ious other  groups.  This  evidence  is  presented  below. 

Certain  investigators  of  recent  time  have  come  to  consider  the  trema- 
todes  of  polyphyletic  origin.  According  to  Faust  (1918)  these  conclusions 
are  the  result  of  "lack  of  study  and  consequent  inability  to  recognize  the 
fundamental  resemblance  of  the  genital,  excretory  and  nervous  sys terns. " 

The  first  to  suggest  relationship  between  the  Monostomata  and  the 
Distomata  was  Monticelli  (1893:149-150)  when  he  called  attention  to  the 
similarity  of  Kollikeria  and  Didymozoon.  More  recently  Ariola  (1906) 
reinforced  this  opinion  by  grouping  Monostoma  fillicolle  Rud.  and  Distoma 
okeni  Kolliker  together  on  the  basis  of  their  anatomical  similarity  even 
though  Monostoma  fillicolle  does  not  possess  an  acetabulum.  MacCallum 
and  MacCallum  (1916)  on  the  basis  of  anatomical  similarity  grouped 
together  the  two  genera  Kollikeria  and  Nematobothrium  altho  Kollikeria 
shows  in  many  cases  well  developed  acetabula  while  Nematobothrium  is 
in  that  respect  typically  monostomatous. 

Cohn  (1904)  in  his  study  of  Monostomum  flavum  Mehlis,  worked  over 
by  Stossich  (1902)  and  placed  in  the  new  genus  Typhlocoelum,  found  a 
well  developed  but  small  ventral  acetabulum  which  he  figures  in  sagittal 
sections.  This  species  on  the  one  hand  is  apparently  very  closely  related 
to  the  genus  Cyclocoelum  and  was  placed  by  Stossich  in  the  same  sub- 
family, Cyclocoelinae.  On  the  other  hand  Cohn  would  transfer  this  to 
the  Fasciolidae  because  of  the  presence  of  the  ventral  acetabulum  which 
he  says  is  diminished  and  in  other  instances  often  lost  because  of  the  shut-in 
habitat  under  which  these  worms  live. 

He  adds  as  was  stated  previously  the  observation  of  a  rudimentary 
mouth  sucker  in  Cyclocoelum  mutabile  and  in  one  other  species  of  this 
group.  Here  he  states  that  Cyclocoelum  mutabile  does  not  lack  a  primary 
sucker  in  many  cases  and  like  the  Cestodarian  Amphilina  has  lost  hold-fast 
organs  because  of  the  lack  of  need  for  such  organs  in  the  cavities  of  the 
body  of  the  host  in  which  habitat  these  worms  are  wont  to  live.  According 


291]  NORTH  AMERICAN  MONOSTOMES  73 

to  this  author  Cyclocoelum  mutabile  and  Typhlocoelum  flavum  are  very 
closely  related  and  because  of  different  stimuli  in  their  respective  habitats, 
viz.:  alveolar  spaces,  abdominal  cavity  and  liver,  occasionally  the  intestine 
for  Cyclocoelum,  and  trachea  and  bronchi  for  Typhlocoelum,  the  acetabu- 
lum of  Cyclocoelum  has  been  lost  while  the  oral  sucker  of  Typhlocoelum 
has  atrophied. 

In  his  earlier  work  (1902)  Cohn  described  Monostomum  oculobium 
collected  from  Vanellus  melanogastrus  as  having  neither  oral  nor  ventral 
suckers  and  relates  it  to  Cyclocoelum  mutabile.  Fuhrmann  (1904)  describes 
a  species,  Bothriogaster  variolaris  collected  from  the  intestine  of  Rostrhamus 
sociabilis,  a  South  American  Falconid,  which  from  his  figures  and  descrip- 
tion appears  to  be  very  similar  to  Monostomum  oculobium  of  Cohn.  He 
states  that  in  regard  to  the  intestinal  crura,  absence  of  the  oral  sucker 
and  the  presence  of  only  a  pharynx  it  is  like  Cyclocoelum  mutabile.  The 
position  of  the  genital  glands  is  not  the  same  but  on  the  other  hand  is  like 
those  of  Monostomum  oculobium  of  Cohn.  But  it  differs  from  Monostomum 
oculobium  in  that  a  ventral  sucker  is  present  which  Fuhrmann  believes 
Cohn  had  overlooked  in  his  species.  Fuhrmann  would  place  Bothriogaster 
variolaris  in  the  sub-family  Syncoelinae  of  the  Fasciolidae. 

Odhner  (1907)  supports  the  view  of  Cohn  and  cites  a  number  of  in- 
stances to  demonstrate  it.  Chief  among  these  are,  first,  his  genus  Apora- 
cotyle  which  is  a  blood  parasite.  He  says  that  this  suckerless  form  has  its 
nearest  relative  in  the  distome  Hapalotrema  constrictum  (Leared),  a  blood 
parasite  of  the  sea  turtle.  Second,  those  inhabiting  the  airsacs  have 
developed  the  hold-fast  organs  to  the  least  degree.  This  includes  the 
Cyclocoelidae  in  which  Odhner  says  all  species  are  without  a  ventral 
sucker  except  for  the  recent  discovery  by  Cohn  of  an  entirely  rudimentary 
acetabulum  in  Typhlocoelum  flavum.  He  adds  that  in  the  Holostomes 
and  Hemistomes  ventral  suckers  have  been  greatly  reduced  and  in  some 
instances  have  disappeared  entirely.  In  further  support  of  this  view  he 
cites  the  reduction  of  the  sucker  in  the  male  Bilharzia  with  the  complete 
loss  of  this  organ  in  Bilharzia  kovalewski,  and  notes  also  the  Echinostome 
like  genus  Pegosomum  which  inhabits  the  gall  duct  and  has  lost  entirely 
the  oral  sucker.  Odhner  believes  that  the  Monostomata  will  be  finally 
split  up  and  appended  to  other  trematode  groups,  i.e.,  to  the  Distomes, 
Amphistomes,  Holostomes  and  perhaps  others. 

In  the  light  of  the  foregoing  one  may  well  ask,  what  is  a  Monostome? 
The  question  has  been  aptly  raised  as  to  what  characters  or  combinations 
of  characters  afford  a  reliable  and  accurate  basis  for  the  natural  classifica- 
tion of  the  trematodes.  On  the  basis  of  the  examples  given  above  the 
presence  or  absence  of  an  acetabulum  can  be  considered  of  relatively 
little  importance  and  if  such  be  the  case  other  factors  must  be  looked  for 
in  an  attempt  to  establish  a  natural  system  of  classification. 


74  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [292 

In  view  of  the  facts  stated  above  the  writer  believes  that  an  accurate 
knowledge  of  the  more  fundamental  systems  of  organs  will  reveal  group 
relationships  which  have  heretofore  passed  unnoticed.  In  the  present 
systematic  groups  homology  of  organs  is  a  factor  which  has  been  generally 
passed  over.  This  can  best  be  demonstrated  by  a  careful  study  of  the 
developing  organs  in  the  early  stages  of  the  life  history  of  the  individual. 
Up  to  this  time  little  has  been  done  on  the  life  histories  of  the  Monosto- 
mata.  Von  Siebold  (1835)  and  Van  Beneden  (1861)  studied  the  early 
stages  of  the  parthenogenetic  phase.  La  Valette  St.  George  (1855)  de- 
scribed under  the  name  of  Monostomumflavum  a  cercaria  which  he  believed 
to  belong  to  this  species.  From  his  descriptions  and  figures  one  can  see 
diagnostic  points  which  tend  to  show  that  this  cercaria  belongs  to  the 
Notocotylidae  on  the  basis  of  the  well  developed  oral  sucker,  the  posses- 
sion of  the  locomoter  pockets  described  by  Looss,  Cort,  and  Faust  for 
Notocotylid  species.  The  fact  that  La  Valette  St.  George  showed  the 
intestine  anastomosed  posteriorly  does  not  furnish  evidence  to  the  contrary 
since  the  crura  of  the  Notocotylid  approach  each  other  in  the  posterior 
end  of  the  worm  and  this  may  easily  be  mistaken  for  anastomosis  or  on  the 
other  hand  the  author  may  have  misinterpreted  the  excretory  ducts  for 
the  crura  of  the  intestine.  The  characteristic  features  are  the  absence  of 
the  pharynx  and  the  presence  of  the  three  eyespots  which  appear  to  be 
characteristic  of  the  Notocotylidae.  In  addition  to  these  Haldemann, 
Leidy,  Cort  and  Faust  have  described  some  six  or  seven  monostome 
cercaria  from  American  hosts  all  of  which  have  been  referred  to  the  Noto- 
cotylidae. While  the  writer  has  had  opportunity  to  study  immature 
stages  of  Notocotylus  urbanensis,  the  preserved  material  has  yielded  only 
few  facts  that  can  be  interpreted  as  of  phylogenetic  importance.  These 
will  be  discussed  in  a  subsequent  section  of  this  paper.  As  yet  no  Mono- 
stome life  history  has  been  demonstrated  experimentally  and  the  develop- 
ment of  the  important  systems  of  organs  has  not  been  followed  in  the  life 
history  of  even  a  single  species.  This  seems  to  the  writer  to  be  a  necessary 
step  to  be  followed  out  in  the  major  families  in  order  to  demonstrate  the 
phylogenetic  relationships  of  the  large  groups. 

INTERRELATIONSHIP  OF  THE  MONOSTOME  FAMILIES 

Before  entering  into  the  discussion  of  the  probable  origin  of  the  Mono- 
stomes  it  seems  fitting  to  discuss  the  interrelationship  of  the  families  as  a 
unit  or  natural  group  of  Trematodes.  A  comparison  of  the  family  diagno- 
ses, given  earlier  in  this  paper,  shows  a  striking  contrast  in  each  of  the 
families  discussed  and  of  the  families  not  included  the  same  striking  con- 
trast may  be  drawn.  No  system  of  organs  is  the  same  in  all  of  the  families 
save  perhaps  the  nervous  system,  so  far  as  it  has  been  made  out,  which  is 
essentially  the  same  in  all  the  trematodes.  The  excretory  system  differs 


293]  NORTH  AMERICAN  MONOSTOMES  75 

in  these  families;  in  the  Cyclocoelidae  it  is  composed  primarily  of  a  large 
half -moon  shaped  bladder  and  ramifying  network  of  anastomosed  tubules. 
In  the  Notocotylidae  a  single  club-shaped  bladder  extends  almost  to  the 
ovary  and  sometimes  a  little  posterior  to  the  excretory  pore  (Notocotylus 
quinqueserialis) ;  at  the  anterior  end  of  this  bladder  two  branches  are  given 
off  which  pass  lateral  to  the  ovary  and  from  these  numerous  side  branches 
are  produced.  In  the  Heronimidae  the  bladder  consists  of  a  large  median 
sac  with  the  pore  in  the  anterior  dorsal  region,  while  in  the  Collyriclidae 
the  bladder  is  single,  club-shaped,  and  branches  near  the  center  of  the 
body.  In  regard  to  the  digestive  system  equally  striking  differences  appear. 
The  Notocotylidae  show  no  trace  of  a  pharynx  while  the  Cyclocoelidae, 
Heronimidae  and  the  Collyriclidae  possess  both  sucker  and  pharynx.  The 
crura  of  the  Cyclocoelidae  anastomose  in  the  posterior  end  of  the  body 
while  in  the  other  families  under  consideration  the  crura  end  blindly. 
Another  characteristic  difference  is  the  presence  of  dermal  glands  in  some 
of  the  Notocotylidae,  while  such  organs  are  unknown  in  the  other  families. 
In  the  genital  system  are  to  be  found  equally  great  characteristic  differ- 
ences in  the  position  of  the  glands  with  respect  to  the  intestinal  crura  as 
well  as  in  the  form  of  the  glands  themselves.  These  and  other  important 
differences  seem  to  indicate  that  these  families  have  arisen  from  different 
lines. 

THE  APPARENT  RELATION  OF  THESE  FAMILIES  TO  OTHER  GROUPS 

Since  the  great  diversity  of  structure  in  this  group  seems  to  indicate 
that  the  monostomes  have  arisen  from  different  sources,  there  remains  to  be 
considered  in  conjunction  with  this  fact  the  close  affinity  of  certain  of  these 
families  to  widely  separated  groups. 

The  finding  of  a  rudimentary  acetabulum  in  Monostomum  flavum 
Mehlis  by  Cohn  and  of  the  well  developed  acetabulum  in  Bothriogaster 
variolaris  by  Fuhrmann  in  the  same  year  together  with  the  similarity  in 
structure  seems  to  indicate  a  relationship  to  the  Fasciolidae  through  the 
Syncoelinae  according  to  Fuhrmann  (1904)  to  which  Bothriogaster  is 
most  closely  related. 

After  a  similar  manner  the  Notocotylidae  find  their  closest  parallels 
among  marine  forms  where  the  genus  Notocotylus  has  anatomically  a  very- 
close  relative  in  Adenogaster  serialis  while  those  Notocotylids  without  the 
ventral  glands  appear  more  like  the  genus  Glyphicephalus. 

The  Heronimidae  stand  alone  in  their  organization  and  do  not  show 
close  relationship  to  any  known  trematodes. 

Attention  was  first  called  to  the  distome  character  of  Collyriclum  faba 
by  Braun  (1892)  and  again  by  Kossack  (1911:577)  who  points  out  the 
relation  of  this  species  to  Distomum  gastrophilum  but  hesitates  to  decide 
whether  it  is  a  natural  one,  thus:  "Indessen  wage  ich  es  vorlaufig  noch 


76  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [294 

nicht  zu  entscheiden,  ob  hier  natiirliche  Verwandtschaft  oder  nur  eine 
Kon vergenzerscheinung  vorliegt. ' ' 

More  recently  Odhner  (1914)  placed  this  genus  in  his  new  family  Trog- 
lotremidae  which  he  characterizes  as  follows:  Mehr  oder  weniger  abge- 
plattete  "Distomen"  oder  "Monostomen"  von  gedrungener  Korperform 
und  2-13  mm  Lange.  Das  ausserste  Hinterende  als  ein  kleiner  "Schwanz- 
anhang"  vorstreckbar.  Bauchflache  flach  oder  etwas  ausgehohlt,  Riicken- 
flache  gewolbt.  Haut  iiber  und  iiber  mit  spitzen  Stacheln  bewaffnet. 
Muskulatur  bei  den  Cystenbewohnern  schwach  entwickelt,  auch  in  den 
Saugnapfen.  Darmapparat  mit  Pharynx,  nicht  allzu  langem  Oesophagus 
and  Darmschenkeln,  die  ein  mehr  oder  weniger  kurzes  Stuck  vor  dem 
Hinterende  endigen.  Exkretionsblase  Y-formig  oder  einfach  schlauchfor- 
mig.  Genitalporus  dicht  am  Vorder-  oder  Hinterrand  des  ev.  Bauch- 
saugnapfes,  median  oder  leicht  lenkseitig.  Cirrusbeutel  meist  fehlend, 
[except  Troglotrema]  Pars  prostatica  und  Samenblase  immer  unter- 
scheidbar.  Hoden  symmetrisch,  in  oder  hinter  der  Korpermitte,  langs 
gestellt.  Ovar  unmittelbar  vor  den  Hoden,  rechtseitig,  [Except  Paragoni- 
mus  westermanni  in  which  amphytypy  occurs]  meist  stark  gelappt  [except 
Troglotrema].  Receptaculum  seminis  und  Laurerscher  Kanal  vorhanden. 
Dotterstocke  meistens  sehr  stark  entwickelt  [except  Collyriclum]  und 
dabei  ausschliesslich  oder  hauptsachlich  unter  der  Ruckenflachs  ausge- 
breitet,  nur  einen  medianen  Streifen  frei  lassend.  Uterus  bald  sehr  lang 
und  stark  hin  und  her  gewunden,  bald  relativ  kurzer  und  mehr  aufge- 
knauelt.  Eier  im  ersteren  Falle  klein,  0.017—0.025  mm  lang,  im  letzteren 
bedeutend  grosser,  von  0.063-0.085,  nach  einigen  Angaben  sogar  bis  0. 12 
(?)  mm  Lange. — Parasiten  von  carnivoren  Saugetieren  oder  von  Vogeln, 
meistens  paarweise  in  cystenahnlichen  Hohlungen." 

This  family  appears  to  be  an  unnatural  grouping.  Of  the  four  genera 
included  three  of  them,  Troglotrema,  Paragonimus  and  Collyriclum, 
show  radical  divergence  from  the  family  diagnosis  as  evidenced  by  the 
fact  that  exceptions  must  be  made  in  order  to  include  them.  In  an  appen- 
dix the  author  adds  to  this  new  family  Renicola  pinguis  which  he  says  is 
the  closest  relative  of  Collyriclum  f aba. 

Jegen  (1917)  cites  the  close  relationship  of  Collyriclum  to  Brandesia 
turgida.  This  author  emends  the  family  diagnosis  of  Odhner  for  the  new 
family  Troglotremidae  as  follows  in  order  to  include  these  two  genera, 
Renicola  and  Brandesia.  "Die  Haut  entweder  mit  spitzen  Stacheln  oder 
mit  Schuppen  durchsetzt.  Bauchsaugnapf  entweder  unmittelbar  vor  oder 
hinter  der  Korpermitte." 

The  present  investigations  do  not  show  the  same  close  relationship 
for  Collyriclum  as  found  by  Odhner  and  Jegen  in  the  family  Troglotremi- 
dae while  it  shows  a  distinct  relationship  to  Brandesia.  This  genus  is 
strikingly  different  from  other  genera  in  Odhner's  family  Troglotremidae. 


295] 


NORTH  AMERICAN  MONOSTOMES 
Table  II.    Probable  Relationships  of  Collyriclidae 


77 


Brachycoelinae 

Collyriclidae 

Plenrogenetinae 

Shape 

Egg-shaped  or  spheri- 
cal 

Hemispherical 

Small    to   medium 
slightly  elongated 

Integument 

Naked  rarely  spinous 

Spinous-in  rows 

Spiny  or  scaled 

Oral  sucker 

Well  developed 

Terminal  small 

Weakly  developed 

Acetabulum 

Well  developed 

Wanting 

Weakly  developed 

Pharynx 

Small 

Smaller  than  sucker 

Poorly  developed 

Crura 

Thin,  small 

Thin,  voluminous 

Never  reaching     pos- 
terior end 

Excretory 

V-shaped 

Large  Y-shaped 

V  or  Y-shaped 

Genital  pore 

Ventral  between  suck- 
ers 

Center  of  ventral  sur- 
face 

Between  suckers,  lat- 
eral 

Copulatory  organs 

Present  or  absent 

Present,    moderately 
developed 

Well  developed 

Testes 

Symmetrical  oval 

Symmetrical,    irregu- 
larly lobed 

Symmetrical  oval 

Ovary 

Lateral,  near  acetabu- 
lum 

Lateral,  anterior,  deep- 
ly lobed 

Lateral,    near   or   an- 
terior to  acetabulum 

Receptaculum 
seminis 

Present 

Wanting  (?) 

Present 

Laurer's  canal 

Present 

Present 

Present 

Vitellaria 

Single  arborescent 
group 

Several  arborescent 
groups  on  each  side 

Simple  arborescent 
group  anterior 
to  crura 

Uterus 

Usually    posterior    to 
testes 

In  general  in  posterior 
body  half 

Usually    in    posterior 
body  half 

Eggs 

Numerous   about   22  M 
long 

Numerous   19  to  21  n 
long 

29  to  34ju  long 
13  to!6/x  broad 

Host 

Mammals,   birds    and 
reptiles 

Birds,  parasitic  in  pairs 
in  cysts 

Amphibia     and     rep- 
tiles.    Renicola  and 
Loxogenes  in  pairs 

78  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [296 

The  position  of  the  genital  pore  as  well  as  the  organology  depicts  it  as 
distinct  from  Collyriclum.  This  study  confirms  the  systematic  position  of 
Brandesia  given  by  Looss  in  that  it  is  more  closely  related  to  the  Pleu- 
rogenetinae.  Collyriclum  is  in  some  respects  closely  related  to  the  Pleuro- 
genetinae  and  in  other  respects  to  the  Brachycoelinae.  The  diagnostic 
characters  of  Collyriclum  are  so  evenly  distributed  between  these  two  sub- 
families that  it  holds  an  intermediate  place  as  shown  in  the  table  opposite. 

Whether  the  interpretation  given  above  is  the  correct  one  remains 
indeed  a  matter  of  conjecture  and  certainly  lacks  much  of  confirmation. 
It  is  difiicult  to  ascertain  from  an  anatomical  study  of  adult  forms  as 
to  whether  acetabula  are  vestigial.  The  most  immature  Cyclocoelidae 
studied  by  the  writer  show  no  trace  of  such  organs.  These  forms  belong 
to  Cyclocoelum  obscurum.  In  more  advanced  stages  of  Cyclocoelum  halli 
the  sucker  is  found  practically  as  well  developed  as  in  the  adult.  Since 
the  material  of  the  immature  stage  of  Cyclocoelum  obscurum  was  not  well 
preserved  conclusions  cannot  be  drawn  from  it.  In  the  immature  stages 
of  Notocotylus  urbanensis  studied  by  the  writer  the  ventral  glands  were 
found  to  develop  after  encystment  of  the  cercariae  and  to  show  no  rela- 
tion in  their  development  to  an  acetabulum.  Much  evidence  on  this 
point  can  yet  be  obtained  by  the  elucidation  of  this  and  other  life  histories. 

It  is  worthy  of  note,  however,  that  in  the  Notocotylidae  the  oral 
sucker  is  well  developed  in  the  cercariae  as  well  as  in  the  adult,  but  instead 
of  a  single  well  developed  acetabulum  the  condition  is  somewhat  varied. 
In  Notocotylus  quinqueserialis  five  rows  of  small  sucking  discs  are  pro- 
vided. In  Notocotylus  attenuatum  three  rows  of  similar  organs  are  present, 
while  in  Nudocotyle  and  Paramonostomum  no  such  sucking  organs  are 
present.  These  species  live  in  a  similar  habitat  (intestine  of  the  muskrat) 
and  under  this  condition  have  developed  in  the  first  instance  different 
numbers  of  these  organs  while  in  the  latter  case  no  such  structures  have 
been  observed.  Nudocotyle  novicia,  however,  presents  other  striking  differ- 
ences which  need  not  be  considered  here.  In  the  cercariae  of  these  forms 
described  notably  by  Cort  (1914)  and  Faust  (1918)  no  such  organs  are 
found  nor  is  there  any  indication  of  their  early  development,  while  in  the 
immature  forms  of  Notocotylus  urbanensis  studied  by  the  writer  these  glands 
are  found  well  along  in  development  soon  after  being  freed  from  the  cyst. 
The  other  organs  of  these  cercariae  correspond  so  well  to  the  adult  struc- 
ture that  there  is  little  doubt  as  to  the  identity  of  the  form.  In  this  case 
then  the  sucking  discs  are  developed  after  the  organism  enters  the  defini- 
tive host.  A  final  decision  of  this  question,  however,  must  await  further 
evidence  and  experimental  demonstration  of  the  life  history. 

The  cases  of  reduction  of  sucking  musculature  cited  by  Cohn  (1904) 
and  Odhner  (1907,  1911)  lead  again  to  the  question  raised  previously  and 
in  the  light  of  the  theory  of  Cohn  and  Odhner  it  is  difficult  to  determine 


297]  NORTH  AMERICAN  MONOSTOMES  79 

if  this  reduction  is  of  phylogenetic  import  or  subject  to  rapid  change  under 
environmental  stimuli.  A  comparison  of  similar  worms  under  different 
conditions  leads  to  the  belief  that  the  sucking  musculature  is  not  subject 
to  such  rapid  and  radical  change  as  indicated  by  Odhner  (1907).  As  shown 
in  an  earlier  part  of  this  paper,  Cyclocoelum  wilsoni  and  Cyclocoelum 
mcarium  from  the  intestine  of  their  host  have  poorly  developed  oral  suckers 
and  no  trace  of  an  acetabulum  while  Cohn  has  found  a  rudimentary  aceta- 
bulum  in  Monostomum  flavum,  a  species  which  inhabits  the  trachea. 

In  the  Heronimidae  which  inhabit  the  lungs  and  especially  the  larger 
bronchi  of  turtles,  the  oral  acetabulum  is  well  developed  while  any  evi- 
dence of  the  presence  of  a  ventral  sucker  has  not  been  obtained.  This 
stands  in  rather  striking  contrast  to  the  statement  of  Odhner  (1907) 
referred  to  above.  Fuhrmann  (1904)  cites  an  interesting  case  in  his  Bothrio- 
gaster  variolaris  which  was  collected  from  the  intestine  of  Rostrhamus 
sociabilis.  This  species  according  to  the  author  has  a  ventral  acetabulum 
but  no  oral  sucker.  A  pharynx,  however,  is  present.  As  stated  pre- 
viously his  species  is  strikingly  similar  to  Monostomum  oculolium  Cohn 
taken  from  Vanellus  melanogastrus  which  Cohn  (1902)  says  is  devoid  of 
sucking  apparatus.  Why  has  the  oral  sucker  of  Bothriogaster  variolaris 
atrophied  if  reduction  is  due  to  habitat  as  stated  by  Cohn  (1902)  and 
Odhner  (1907)? 

Another  interesting  correlation  is  found  among  the  Notocotylidae  and 
the  Pronocephalidae  both  of  which  inhabit  the  intestine.  Among  the 
Notocotylidae  are  forms  which  late  in  life  develop  the  ventral  holdfast  or 
adhesive  glands  and  those  without  such  glands,  both  types  of  which  have 
been  found  in  the  alimentary  tract  of  the  muskrat.  Linton  (1910)  reports 
a  species  Barisomum  erubescens  from  the  intestine  of  three  tropical  fish 
which  show  no  sign  of  any  sucking  organ  save  the  oral.  Of  the  several 
genera  of  the  Pronocephalidae  taken  from  the  intestine  of  Chelone  midas 
only  Adenogaster  shows  any  trace  of  accessory  adhesive  apparatus.  On 
the  other  hand  Odhner  (1911)  found  reason  to  ally  the  Angiodictyidae  a 
closely  related  family  to  the  distomes  on  account  of  a  weakly  developed 
acetabulum  found  in  Haplorchis  carhinus  Looss. 

As  was  stated  previously  Odhner  (1907)  proved  beyond  doubt  the 
presence  of  both  pharynx  and  oral  sucker  in  Didymozoon  scombri  Tschbg. 
but  found  there  no  ventral  sucker.  Four  years  later  Ariola  (1906)  asserts 
the  Didymozoon  nature  of  Kollikeria  (Distoma)  okeni  (Kolliker)  which 
he  states  is  synonymous  with  Monostomum  fillicolle  Rud.  In  the  Parona 
material  reported  as  Kollikeria  in  which  there  were  many  distomes  accord- 
ing to  this  author,  he  finds  a  single  form  without  the  acetabulum. 

On  the  other  hand  Collyriclum  faba  (Bremser)  and  Collyriclum  colei 
Ward,  other  cyst  living  trematodes,  have  no  acetabula  but  present,  however, 
a  well  developed  oral  sucker.  It  is  difficult  to  interpret  how  worms  which 


80  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [298 

live  under  such  similar  conditions  as  the  Didymozoonidae  and  the  Colly- 
riclidae  could  by  the  effect  of  habitat  alone  become  so  totally  different. 

That  the  habitat  in  which  the  worm  lives  is  a  factor  in  the  modification 
cannot  be  disputed  but  is  certainly  only  one  factor  which  contributes  to 
the  modification.  What  makes  up  the  aggregate  of  factors  in  a  given  case 
could  be  only  a  matter  of  conjecture.  Recent  experimental  investigation, 
however,  has  shown  that  factors  influencing  modifications  of  an  individual 
or  race  may  be  both  external  and  internal  and  that  the  change  produced 
may  be  gradual  or  occur  as  a  mutation  in  which  case  little  or  no  trace  may 
be  left  to  depict  the  ancestral  route.  While  the  writer  is  inclined  to  look 
upon  the  loss  of  sucking  musculature  as  a  gradual  change  brought  about 
by  a  group  of  factors  among  which  the  habitat  seems  to  have  played  an 
important  part,  there  is  every  reason  to  believe  that  sudden  radical  re- 
arrangements have  taken  place  and  these  are  no  doubt  responsible  for  many 
of  the  variant  forms.  While  there  is  good  reason  to  believe  that  the  Mono- 
stomata  have  arisen  from  highly  divergent  groups  the  evidence  seems  as 
yet  about  equally  divided  and  the  final  decision  must  necessarily  rest  on 
further  studies  of  the  anatomy  and  life  history  of  members  of  this  and 
other  groups. 

The  systematic  arrangement  used  in  the  earlier  part  of  this  paper  is 
essentially  that  employed  by  Liihe  (1909),  Kossack  (1911)  and  Ward 
(1918),  which  for  the  above  stated  reason  it  seemed  best  to  preserve  at 
least  for  the  present.  It  is  hoped  that  interest  in  this  aberrant  group  will 
increase  and  that  careful  studies  will  result  either  in  the  preservation  of 
these  forms  as  a  natural  taxonomic  group  or  in  their  separation  and  subse- 
quent distribution  among  other  well  organized  units  to  which  they  are  truly 
related. 


299]  NORTH  AMERICAN  MONOSTOMES  81 

SUMMARY 

I.  Monostomes  from  North  American  land  and  fresh  water  hosts  have 

been  studied. 
II.  Nine  new  species  have  been  described  in  detail. 

III.  The  knowledge  of  their  anatomy  and  life  history  is  greatly  increased. 

1.  Both  oral  sucker  and  pharynx  are  present  in  the  Cyclocoelidae. 

2.  In  the  genera  of  Cyclocoelidae  studied  the  receptaculum  seminis 

is  a  constant  feature  while  Laurer's  canal  is  not  present. 

3.  The  origin  of  the  ventral  glands  in  Notocotylus  urbanensis  is 

clearly  shown  in  early  stages  of  development. 

IV.  The  discovery  of  well  developed  miracidia  in  Collyriclum  colei  renders 

improbable  Jegen's  account  of  the  life  history  of  Collyriclum  faba. 
V.   A  careful  study  of  the  anatomy  of  the  Cyclocoelidae,  the  Notocotyli- 
dae,  the  Collyriclidae,  and  the  Heronimidae  demonstrates  clearly 
that  they  are  not  immediately  related. 

1.  The  Cyclocoelidae  are  probably  allied  to  the  Fasciolidae. 

2.  The  Notocotylidae  are  closely  related  to  the  Pronocephalidae 

not  merely  in  general  organology  but  especially  in  the  presence 
of  peculiar  ventral  glands. 

3.  A  study  of  the  organology  of  the  Collyriclidae  demonstrates 

clearly  their  direct  relationship  to  the  Pleurogenetinae. 

4.  The  Heronimidae  do  not  show  immediate  relationship  to  any 

known  trematodes. 

VI.  The  monostomes  are  a  heterogeneous  group  and  must  ultimately  be 
distributed  among  other  groups  in  accordance  with  their  funda- 
mental relationships. 


82  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [300 


BIBLIOGRAPHY 
ARIOLA,  V. 

1906.    Monostoma  filicolle  Rud.  e  Distoma  okeni  K6lliker.    Zool.  Anz.,  30:185-186. 
ARNSDORFF,  A. 

1908.    Monostomum  mcarium.  Centralbl.  Bakt.  Par.,  Abt.  I,  Orig.,  47:362-366;  2  fig. 
BAIRD,  W. 

1853.    Catalogue  of  the  species  of  entozoa  or  intestinal  worms  contained  in  the  collec- 
tion of  the  British  Museum.   London;  2  pi. 
BABKER,  F.  D. 

1915.  Parasites  of  the  American  Muskrat  (Fiber  zibethicus).     Jour.  Par.,  1:184-197; 
2  pi,  4  figs. 

1916.  A  new  Monostome  Trematode  Parasitic  in  the  Muskrat  with  a  Key  to  the 
Parasites  of  the  American  Muskrat.   Trans.  Amer.  Mic.  Soc,  35 :175-184;  1  pi. 

BARKER,  F.  D.  and  LAUGHLIN,  J.  W. 

1911.    A  New  Species  of  Trematode  from  the  Muskrat,  Fiber  zibethicus.    Trans.  Amer. 

Mic.  Soc.,  30:261-274;  1  pi. 
BARKER,  F.  D.  and  PARSONS,  SUSANNE. 

1914.    A  new  species  of  Monostome  from  the  Painted  Terrapin,  Ckrysemys  marginata. 
Zool.  Anz,  45:193-194. 

1917.  A  Monostome  Lung  Fluke  from  the  Painted  Terrapin,  Chrysemys  marginata  Agas- 
siz.   Trans.  Amer.  Mic.  Soc,  36:55-66;  2  pi. 

VAN  BENEDEN,  P.  J. 

1861.    M6moire  sur  les  vers  intestinaux.    Suppl.  C.  r.  Acad.  Sci,  2:1-376. 
BLANCHARD,  R. 

1903.    Experiences  et  observations  sur  la  marmotte  en  hibernation.    VI.  Observations 

sur  les  parasites  en  general.    C.  r.  Soc.  biol,  55 :1124-26. 
BLOCH,  M.  E. 

1782.    Abhandlung  von  der  Erzeugung  der  EingeweidewUrmer.    Berlin.    54  pp.;  10  pi. 
BLOCHMANN,  F. 

1896.    Die  Epithelialfrage  bei  Cestoden  und  Trematoden.    Hamburg.    12  pp.;  2  pi, 

Ifig. 
BRANDES,  G. 

1891.  Zum  feineren  Bau  der  Trematoden.    Zeit.  wiss.  Zool,  53:558-577;  1  pi. 

1892.  Revision  der  Monostomiden.   Centrlbl.  Bakt.  Par,  12:504-511. 
BRAUN,  M. 

1889-1893.    Trematodes,  hi  Bronn's  Klass.  Ordn.  d.  Thier-Reichs.  4,  Abt.  la:306-925. 

1893.  II.  Bericht  iiber  thierische  Parasiten.    Centrlbl.  Bakt.  Par,  13:59-68. 

1893a.  Die  Wohnsitze  der  endoparasitischen  Trematoden.    Centrlbl.  Bakt.  Par,  13: 

465-468. 

1901.    Trematoden  der  Chelonier.   Mitt.  zool.  Mus.  Berlin,  2,  58  pp.;  2  pi,  2  fig. 
1901a.  Zur  Kenntniss  der  Trematoden  der  Saugethiere.    Zool.  Jahrb,  Syst,  14:311- 

348;  2  pi. 
BREMSER,  M. 

1831.    Schmalz,  XIX  Tabulae  Anatomian  entozoorum  illustrantes.    Dresdae  et  P 

Lipsiae;  11-16.    (Not  available.) 
COBBOLD,  T.  S. 

1860.    Synopsis  of  the  Distomidae.   Jour.  Proc.  Linn.  Soc.  Lond.  Zool,  5:1-56. 


301]  NORTH  AMERICAN  MONOSTOMES  83 

1864.    Entozoa;  An  introduction  to  the  study  of  Helminthology.    London.    480  pp.; 

21  pi.,  82  text  fig. 
COHN,  L. 

1902.    Mittheilungen  fiber  Trematoden.    Zool.  Anz.,  25:712-718;  9  fig. 
1904.    Helminthologische  Mitteilungen  II.   Arch.  Naturg.,  1:229-251. 
COLE,  L.  J. 

1911.    A  Trematode  Parasite  of  the  English  Sparrow  hi  the  U.  S.  Bull.  Wise.  Nat.  Hist. 
Soc.,  9:42-48;  2  pi. 

CORT,  W.  W. 

1913.  Notes  on  the  Trematode  Genus  Clinostomum.     Trans.  Amer.  Mic.  Soc.,  32: 
169-182;  1  pi. 

1914.  Larval  Trematodes  from  North  American  Fresh-Water  Snails.     Jour.  Par., 
1:65-84;  15  figs. 

1915.  Some  North  American  Larval  Trematodes.    HI.  Biol.  Monogr.,  1 :446-532;  8  pi. 
CREPLIN,  F.  C.  H. 

1829.    Filariae  et  Monostomi  speciem  novam  in  Balaena  rosirata  repertam.     Nova 

acta  Phys.-med.  Acad.  Nat.  curios.,  Bonnae,  14:871-882;  1  pi. 
DDESING,  K.  M. 

1839.    Neue  Gattungen  von  Binnenwiirmern.    Ann.  Wien.  Mus.  Naturg.,  2:219-242; 
7  pi. 

1850.    Systema  Helminthum.    Vienna;  1,  679  pp. 

1858.  Revision  der  Myzhelminthen:  Trematoden.       Sitz.  Akad.  Wiss.  Wien,  math.- 
naturw.  Cl.,  32:207-390;  2  pi.. 

1859.  Nachtrage  u.  Verbesserungen  zur  Revision  der  Myzhelminthen.     Sitz.   Akad. 
Wiss.  Wien,  math-naturw.  Cl.,  35:421-451. 

DUJARDIN,  F. 

1845.    Histoire  naturelle  des  helminthes  ou  vers  intestinaux.    Paris.    654  pp. 
FAUST,  E.  C. 

1918.    Life  History  Studies  on  Montana  Trematodes.    HI.  Biol.  Monogr.,  4:1-120;  9  pi. 
FILIPPI,  F.  DE 

1856.    Quelques  nouvelles  observations  sur  les  larves  des  tr6matodes.    Ann.  sci.  nat, 
Zool,  (4)  6:83-86.    [Translation,  Ann.  Mag.  Nat.  Hist.,  (2)  20:129-132.] 

1859.    Troisie"me  mSmoire  pour  servir  a  1'histoire  gen6tique  des  tr6matodes.     Mem. 

Accad.  sci.  Torino,  (2)  18:201-232;  3  pi. 
FROLICH,  J.  A.  VON. 

1789.  Beschreibung  einiger  neuen  Eingeweidewiirmer.    Naturforscher.,  Halle,  24:101- 
162;  4  pi. 

FUHRMANN,  O. 

1904.    Neue  Trematoden.   Centrlbl.  Bakt.  Par.,  Abt.  I,  Orig.,  37:58-64;  4  fig. 
GMELIN,  J.  F. 

1790.  Caroli  a  Linne  Systema  Naturae,  Vermes.    13  ed.,  1 :3021-3909. 
GOEZE,  J.  A.  E. 

1782.    Versuch   einer   Naturgeschichte    der    Eingeweidewtirmer    thierischer    Korper. 

Blankenburg.    471  pp. ;  44  pi. 
HARRAH,  E.  C. 

1921.    Two  new  Monostomes  from  Asia.    Jour.  Par.,  7:162-165;  2  fig. 
HOYLE,  W.  E. 

1888.    Trematoda.   Encycl.  Brit.,  N.  Y.    9  Ed.,  23:535-540. 
JA'GERSKIOLD,  L.  A. 

1891.    tiber  den  Bau  des  Ogmogaster  plicatus  (Creplin)    (Monostomum  plicatum  Creplin) 
K.  Svensk.  Vetensk,-Acad  Handl.?  Stockholm,  24:1-32;  2  pi. 


84  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [302 

JEGEN,  G. 

1917.  Collyridum  faba  (Bremser)  Kossack.    Ein  Parasit  der  Singvogel,  sein  Bau  und 
seine  Lebensgeschichte.    Zeit.  wiss.  Zool.,  117:460-553;  2  pi. 

JOHNSTON,  S.  J. 

1916.     On  the  Trematodes  of  Australian  Birds.     Jour.  Proc.  Roy.  Soc.  N.  S.  W.,  50: 

187-261;  11  pi. 
KOSSACK,  W. 

1910.  Neue  Distomen.    Centrlbl.  Bakt.  Par.,  Abt.  I,  Orig.,  56:114-120;  4  fig. 

1911.  tiber  Monostomiden,  Zool.  Jahrb.,  Syst.,  31 :493-590;  3  pi. 
LAHILLE,  F. 

1918.  Nota  sobre  Monostoma  mutabile  y  la  clasificacion  general  de  los  Trematodes. 
Buenos  Aires.    Physis:  Rev.  Soc.  Arg.  Ci.  Nat.,  4:328-331. 

LANG,  A. 

1880.    Untersuchungen  zur  vergleichenden  Anatomic  und  Histologie  des  Nervensystems 

der   Platyhelminthen.    II.  Uber  das  Nervensystem  der  Trematoden.     Mitt. 

Zool.  Stat.  Neapel,  2:28-52;  3  pi. 
LA  VALETTE  ST.  GEORGE,  A.  J.  H.  VON 

1855.  Symbolae  ad  trematodum  evolutionis  historiam.     Berolini,  39  pp.;  2  pi. 
LEIDY,  Jos. 

1856.  A  Synopsis  of  Entozoa  and  some  of  their  Ectocongeners  observed  by  the  author. 
Proc.  Acad.  Nat.  Sci.  Phila.,  8:42-58. 

1858.  Contributions  to  Helminthology.   Proc.  Acad.  Nat.  Sci.  Phila.,  10:110-112. 

1877.  On  Flukes  infesting  Molluscs.    Proc.  Acad.  Nat.  Sci.  Phila.,  29:200-202. 

1884.  Distoma  and  Filariae.    Proc.  Acad.  Nat.  Sci.  Phila.,  36:47-48. 

1885.  On  some  parasitic  worms  of  birds.    Proc.  Acad.  Nat.  Sci.  Phila.,  37:9-11. 
1887.  Notice  of  some  parasitic  worms.    Proc.  Acad.  Nat.  Sci.  Phila.,  39:20-24. 

1890.  Notices  of  Entozoa.    Proc.  Acad.  Nat.  Sci.  Phila.,  42:410-418. 

1904.    Researches  in  helminthology  and  parasitology.    Smithson.  Misc.  Coll.,  46:1-281. 

[Leidy,  1904,  is  an  exact  reprint  of  all  his  original  papers.] 
LINTON,  EDWARD. 

1910.    Helminth  Fauna  of  the  Dry  Tortugas.    II.  Trematodes.  Carnegie  Inst.  Pub., 

133:11-98;  28  pi. 

LONNBERG,  E. 

1891.  Mitteilungen  iiber  einige  Helminthen  aus  dem  zool.    Museum  der  Universitat 
zu  Kristiania.    Verh.  biol.  Ver.  Stockholm,  3:64-78;  1  pi. 

Looss,  A. 

1899.  Weitere  Beitrage  zur  Kenntniss  der  Trematoden-Fauna  Aegyptejis,  zugleich 
Versuch  einer  natiirlichen  Gliederung  des  Genus  Distomum  Retzius.     Zool. 
Jahrb.,  Syst.,  12:521-784;  9  pi. 

1901.  Natura  doceri,  eine  Erklarung  und  Begrundung  einiger  Grundsatze,  welche  mich 
bei  meinem  "Versuch  einer.natiirlichen  Gleiderung  des  Genus  Distomum  Retzius" 
geleitet.    Centrlbl.  Bakt.  Par.,  Abt.  I,  29:191-210. 

1902.  tlber  neue  und  bekannte  Trematoden  aus  Seeschildkroten.    Zool.  Jahrb.,  Syst., 
16:411-894;  12  pi. 

LtiHE,  M. 

1900.  [Review  of]  Looss,  A.,  Weitere  Beitrage  etc.     Centrlbl.   Bakt.   Par.,  Abt.  1, 
28:458-466. 

1901.  tfber  Monostomum  orUculare.    Centrlbl.  Bakt.  Par.,  Abt.  1,  29:49-60;  5  fig. 
1901  a.   Zwei  neue  Distomen  aus  indischen  Anuren.     Centrlbl.  Bakt.  Par.,  Abt.  1, 

30:166-177;  5  fig. 


303]  NORTH  AMERICAN  MONOSTOMES  85 

1909.    Parasitische  Plattwiirmer.     Brauer,  Die  Siisswasserfauna  Deutschlands,   17, 

217 pp.;  188  fig. 
MACCALLUM  G.  A.  and  MACCALLUM,  W.  G. 

1916.    The  family  Koellikeriadae  (Didymozoidae)  Mont.    Zool.  Jahrb.,  Syst.,  39:141- 

168;  3  pi. 
MACCALLUM,  W.  G. 

1902.    Heronimus  chelydrae,  nov.  gen.,  nov.  sp.    A  new  Monostome  parasite  of  the 

American  snapping  turtle.  Centrlbl.  Bakt.  Par.,  Abt.  I,  Orig.,  32:632-636;  2  fig. 
MONTICELLI,  F.  S. 

1888.    Saggio  di  una  morfologia  dei  trematodi.    Tesi  per  ottenere  la  privata  docenza 
in  zoologia  nella  R.  Universita  di  Napoli.  130  pp. 

1892.  Studii  sui  trematodi  endoparassiti.     Dei  Monostomum  del  Box  salpa.     Atti. 
Accad.  sci.    Torino,  27:514-534;  1  pi. 

1892a.  Studii  sui  trematodi  endoparassiti.     Monostomum  cymbium  Diesing.     Mem. 

Accad.  sci.  Torino,  42:683-727;  1  pi. 
1892b.  Studii  sui  trematodi  endoparassiti;  sui  genere  Notocotyle  Diesing.    Boll.  Soc.  nat. 

Napoli,  6:28-46. 

1893.  Studii  sui  Trematodi  endoparassiti.    Primo  contribute  di  osservazioni  sui  Dis- 
tomidi.    Zool.  Jahrb.,  Suppl.  3;  229  pp.;  8  pi.,  3  fig. 

ODHNER,  T. 

1900.    Aporocotyle  simplex  n.g.n.  sp.,  ein  neuer  Typus  von  ektoparasitischen  Trematoden. 

Centrlbl.  Bakt.  Par.,  Abt.  1,  27:62-66;  1  fig. 

1905.    Die  Trematoden  des  arktischen  Gebietes.     Fauna  Arctica,  4:291-372;  3  pi.,  4  fig. 
1907.    Zur  Anatomic  der  Didymozoen;  ein  getrenntgeschlechtlicher  Trematode  mit 
rudimentarem  Hermaphroditismus.    Zool.  Stud.  Tullberg,  p.  309-342;  1  pi.,  6  fig. 
1911.    Zum  naturlichen  System  der  digenen  Trematoden.  I.    Zool.  Anz.,  37:181-191. 
1914.    Die  Verwandtschaftsbeziehungen  der  Trematodengattung   Paragonimus   Bra. 

Zool.  Beitr.  aus  Uppsala,  3:231-245;  5  fig. 
OSBORN,  H.  L. 

1911.    On  the  Distribution  and  Mode  of  Occurrence  in  the  United  States  and  Canada  of 
Clinostomum  marginatum,  a  Trematode  Parasitic  in  Fish,  Frogs,  and  Birds. 
Biol.  Bull.,  20:350-366;  1  pi. 
PRATT,  H.  S. 

1902.    Synopses  of  North  American  invertebrates.  12.  The  trematodes.     Am.  Nat., 

36:887-910,  953-979. 
RANSON,  B.  H. 

1920.    Synopsis  of  the  Trematode  family  Heterophyidae  with  descriptions  of  a  new 

genus  and  five  new  species.    Proc.  U.  S.  Nat.  Mus.,  57:527-573;  33  fig. 
RUDOLPHI,  C.  A. 

1801.    Beobachtungen  iiber  die  Eingeweidewiirmer.     Arch.  Zool.  Zoot,  2:1-65. 
1809.    Entozoorum  sive  vermium  intestinalium  historia  naturalis.    2,  457  pp. 
1819.    Entozoorum  synopsis  cui  accedunt  mantissa  duplex  et  indices  locupletissimi. 
811  pp. 

SCHRANZ,  F.  VON  P. 

1788.    Verzeichniss  der  bisher  hinlanglich  bekannten  Eingeweidewurmer,  nebst  einer 

Abhandlung  tiber  ihre  Anverwandtschaften.  Miinchen,  166  pp. 
SIEBOLD,  C.  T.  E.  VON 

1835.    Helminthologische  Beitrage.    Archiv  Naturg.,  1:45-84;  1  pi. 
SKRJABIN,  K.  I. 

1913.    Vogeltrematoden  aus  Russich  Turkestan.    Zool.  Jahrb.,  Syst.,  35:351-388;  2  pi. 

1913a.  Tracheophilus  sisowi  n.g.  n.  sp.    Centrlbl.  Bakt.  Par.,  Abt.  I,  Orig.,  69:90-94;  1  pi. 


86  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [304 

STAFFORD,  J. 

1900.    Some  undescribed  Trematodes.    Zool.  Jahrb.,  Syst,  13:399-414;  1  pi. 

1902.    Cephalogonimus  americanus  (new  species).    Centrlbl.  Bakt.  Par.,  Abt.  I,  Orig., 

32:719-725;  1  pi. 
STILES,  C.  W.  and  HASSALL,  A. 

1894.  A  preliminary  catalogue  of  the  parasites  contained  in  the  collections  of  the 
United  States  Bureau  of  Animal  Industry,  United  States  Army  Medical  Museum, 
Biological  Department  of  the  University  of  Pennsylvania  (Coll.  Leidy)  and  in 
Coll.  Stiles  and  Coll.  Hassall.  Vet.  Mag.,  1:245-253,  331-354. 

1908.  Index-Catalogue  of  Medical  and  Veterinary  Zoology;  Subjects  Trematoda  and 
Trematode  diseases.   Hygienic  Lab.,  Bull.  37 :401. 

STOSSICH,  M. 

1902.    H  Monostomum  mutabile  Zeder  e  le  sue  forme  affine.    Boll.  Soc.  adriat.  sci.  nat. 

Trieste,  21:1^0;  9  pi. 
STUNKAED,  H.  W. 

1917.  Studies  on  North  American  Polystomidae,  Aspidogastridae,  and  Paramphistomi- 
dae.    111.  Biol.  Monogr.,  3-281-394;  11  pi. 

1919.    On  the  specific  Identity  of  Heronimus  chelydrae  MacCallum  and  A  orchis  extensus 

Barker  and  Parsons.    Jour.  Par.,  6:11-18;  2  pi. 
TASCHENBERG,  O. 

1879.    Didymozoon,  eine  neue  Gattung  in  Cysten  lebender  Trematoden.    Ztschr.  ges. 

Naturw.,  5:605-617. 
TYZZER,  E.  E. 

1918.  A  monostome  of  the  genus  Collyriclum  occuring  in  the  European  sparrow,  with 
observations  on  the  development  of  the  ovum.    Jour.  Med.  Res.,  38:267-292; 
4  pi. 

VAILLANT,  L. 

1863.    Note  sur  deux  helminthes  tre*matodes  observes  chez  la  sirfcne  lacertine.    C.  r.  Soc. 

bid.,  4:6-7. 
1863a.  Note  sur  quelques  helminthes  de  la  sir&ne  lacertine.    Ann.  sci.  nat.,  Zool.,  19: 

347-350,  1  pi. 
WARD,  H.  B. 

1909.  The  Influence  of  Hibernation  and  Migration  on  Animal  Parasites.    Proc.  7. 
Internat.  Zool.  Cong.,  12  pp. 

1917.  On  the  Structure  and  Classification  of  North  American  parasitic  Worms.  Jour. 
Par.,  4:1-12;  1  pi. 

1918.  Parasitic  Flatworms.    In  Ward  and  Whipple,  Fresh  Water  Biology.    Pp.  365- 
453;  114  fig. 

1921.    A  New  Blood  Fluke  from  Turtles.   Jour.  Par.,  7:114-129;  1  pi. 
WARD,  H.  B.  and  HIRSH,  E.  F. ! 

1915.    The  species  of  Paragonimus  and  their  differentiation.    Ann.  Trop.  Med.  Par., 

9:109-162;  5  pi. 
WEDL,  C. 

1857.  Anatomische  Beobachtungen  tiber  Trematoden.  Sitz.  Akad.  wiss.  Wien., 
math.-naturw.  Cl,  26:241-278;  4  pi. 

WlLLEMOES-SUHM,  R.  VON 

1873.    Helminthologische  Notizen  III.  (II  t)ber  den  Bau  und  den  Embryo  des  Mono- 
stomum f  aba  Brs.)   Zeit.  wiss.  Zool.,  23:332-335;  1  fig. 
ZEDER,  J.~G.  H. 

1800.  Erster  Nachtrag  zur  Naturgeschichte  der  Eingeweidewurmer,  mit  Zufassen  und 
Anmerkungen  herausgegeben.  Leipzig.  320  pp. 

1803.    Anleitung  zur  Naturgeschichte  der  Eingeweidewurmer.    Bamberg.    432pp. 


88  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [306 


DESCRIPTION  OF  PLATES 

LIST  OF  ABBREVIATIONS 

c  cirrus  ov  ovary 

cm  circular  muscle  p  pharynx 

cp  cirrus  pouch  pp  prepharynx 

g  ventral  glands  rs  receptaculum  seminalis 

ga  genital  atrium  ru  receptaculum    seminalis 

i  intestinal  crura  uterinum 

Im  longitudinal  muscle  sg  shell  gland 

m  mouth  u  uterus 

o  ootype  v  vas  deferens 

e  esophagus  vd  vitelline  duct 

om  oblique  muscle  vr  vitelline  reservoir 

os  oral  sucker  w  wall  of  excretory  tubule 

All  drawings  were  made  by  the  aid  of  either  a  camera  lucida 
or  an  Edinger  drawing  apparatus. 


3071  NORTH  AMERICAN  UONOSTOUES  89 


PLATE  I 


90  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [308 


PLATE  I 

Fig.    1.  Cyclocoelum  leidyi,  dorsal  view.     X12. 
Fig,    2.  Portion  of  the  egg  filled  uterus  of  Cyclocoelum  leidyi.     X45. 

Fig.    3.  Cyclocoelum  mutabile  (Zeder).    Specimen  No.  284  from  Mehlis  Collection,  dorsal 
view.  XI 2. 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


VOLUME  VII 


HARRAH       NORTH  AMERICAN  MONOSTOMES         PLATE  I 


309]  NORTH  AMERICAN  UONOSTOMES  91 


PLATE  II 


92  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [310 


PLATE  II 

Fig.    4.  Cydocoelum  psetidomicroslomum,  ventral  view.    X 12. 
Fig.    5.  Cydocoelum  halli,  ventral  view.    X12. 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


VOLUME  VII 


HARRAH       NORTH  AMERICAN  MONOSTOMES       PLATE  II 


311]  NORTH  AMERICAN  MONOSTOMES  93 


PLATE  III 


94  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [312 


PLATE  III 

Fig.    6.  Cydocoelum  wilsoni,  ventral  view.   X 12. 
Fig.    7.  Cydocoelum  cuneatum,  dorsal  view.    X 12. 
Fig.    8.  Cydocoelum  obscurum,  ventral  view.    X 17. 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


VOLUME  VII 


HARRAH       NORTH  AMERICAN  MONOSTOMES      PLATE  III 


313]  NORTH  AMERICAN  MONOSTOMES  95 


PLATE   IV 


96         •  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [314 


PLATE  IV 

Fig.    9.  Cyclocoelum  macr orchis,  ventral  view.    X15. 

Fig.  10.  Cyclocoelum  Iriangularum,  ventral  view.    X 12. 

Fig.  11.  Cyclocoelum  halli,  young  specimen,  ventral  view.    X23. 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


VOLUME  VII 


o    \r»L«r««FX  11 

HARRAH       NORTH  AMERICAN  MONOSTOMES      PLATE  IV 


315]  NORTH  AMERICAN  MONOSTOMES  97 


PLATE  V 


98  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [316 


PLATE  V 

Fig.  12.  Cross  section,  immature  specimen  of  Notocotylus  urbanensis.   X 190. 

Fig.  13.  Spines  of  Paramonostomum  echinum,  front  view.  X  700. 

Fig.  14.  Notocotylus  urbanensis,  young  specimen,  partial  lateral  view.   X95. 

Fig.  15.  Paramonostomum  echinum,  ventral  view.  X  87. 

Fig.  16.  Spines  of  Paramonostomum  echinum,  lateral  view.    X700. 

Fig.  17.  Notocotylus  urbanensis,  immature  stage,  ventral  view.    X 150. 

Fig.  18.  Notocotylus  urbanensis,  ventral  view.    X44. 

Fig.  19.  Notocotylus  urbanensis,  young  specimen,  dorsal  view.    X120. 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


VOLUME  VII 


17    \V        "Vr  18  ^ ^  19 

HARRAH       NORTH  AMERICAN  MONOSTOMES        PLATE  V 


317|  NORTH  AMERICAN  MONOSTOMES  99 


PLATE  VI 


100  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [318 


PLATE  VI 

All  figures  magnified  92  times 

Fig.  20.  Ovarian  complex,  Cyclocoelum  halli,  drawing  from  wax  reconstruction. 

Fig.  21.  Ovarian  complex,  Cyclocoelum  obscurum,  drawing  from  toto,  same  specimen  as  in 

figure  8. 

Fig.  22.  Ovarian  complex  Cyclocoelum  obliquum,  drawing  from  wax  reconstruction. 
Fig.  23.  Ovarian  complex,  Cyclocoelum  problematicum,  drawing  from  toto   mount  of  No. 

2449   Berlin  Museum. 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


VOLUME  VII 


HARRAH       NORTH  AMERICAN  MONOSTOMES      PLATE  VI 


319] 


NORTH  AMERICAN  MONOSTOMES 


101 


PLATE  VII 


*:-y     .  v  s^s%.'  ^ 

*       *   ?    .,»    jiS1*    ,«oa^^  *          f      ^m      "     ** 

102  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [320 


PLATE  VII 

Fig.  24.  Ovarian  complex,  Cydocodum  cuneatum,  anterior  view.     X92. 

Fig.  25.  Frontal  section,  showing  structure  of  body  wall.  X  435. 

Fig.  26.  Ovarian  complex,  Haematotrephus  similis,  partial  anterior  view  from  above.    X92. 

Fig.  27.  Ovarian  complex,  Cydocodum  pseudomicrostomum,  dorsal  view.   X92. 

Fig.  28.  Frontal  section,  anterior  end  of  Haematoirephus  similis.   X145. 

Fig.  29.  Drawing  of  wax  reconstruction  of  anterior  end  of  Cydocodum  dongatum.   X 108. 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 

•  vr 


VOLUME  VII 


HARRAH       NORTH  AMERICAN  MONOSTOMES    PLATE  VII 


321]  NORTH  AMERICAN  MONOSTOMES  103 


PLATE  VIII 


104  ILLINOIS  BIOLOGICAL  MONOGRAPHS  (322 


PLATE  VIII 
All  figures  magnified  44  times 

Fig.  30.  Ventral  view  of  anterior  end  of  Cydocoelum  pseudomicrostomum. 

Fig.  31.  Ventral  view  of  anterior  end  of  Cydocoelum  brazilianum. 

Fig.  32.  Dorsal  view  of  anterior  end  of  Cydocoelum  mutabile. 

Fig.  33.  Ventral  view  of  anterior  end  of  Cydocoelum  leidyi. 

Fig.  34.  Ventral  view  of  anterior  end  of  Cydocoelum  elongatum. 

Fig.  35.  Ventral  view  of  anterior  end,  of  Cydocoelum  brazilianum,  cirrus  extruded. 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


VOLUME  VII 


HARRAH       NORTH  AMERICAN  MONOSTOMES  PLATE  VIII 


323|  NORTH  AMERICAN  MONOSTOMES  105 


PLATE  IX 


106  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [324 


PLATE  IX 

Fig.36-42.  Inclusive.    Consecutive  20  micra  sections  of  oral  sucker,  Cydocoelum  halli.    X71. 
Fig.  43.  Cross  section  of  oral  sucker,  Cydocoelum  pseudomicrostomum.    X90. 
Fig.  44.  Cross  section  through  anterior  portion  of  oral  sucker,  Cydocoelum  dongatum.    X90. 
Fig.  45.  Cross  section  through  genital  atrium,  Cydocoelum  elongatum.    Xl2. 
Fig.  46.  Frontal  section,  Cydocoelum  elongatum.    X105. 

Figs.  47  &  48.  Cross  sections  of  oral  sucker  of  Cydocoelum  elongatum,  posterior  to  that  in 
figure  44.  X90. 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


VOLUME  VII 


36 


NORTH  AMERICAN  MONOSTOMES     PLATE  IX 


VITA 

Douglass  High  School  1904-1908. 

A.  B.  Southwestern  College  1913. 

Instructor,  Sumner  County  High  School,  Wellington,  Kansas, 
1913-1917. 

Research  Assistant  in  Zoology,  University  of  Illinois  1917-1919. 

A.  M.  University  of  Illinois  1919. 

Elected  to  membership  in  the  Society  of  Sigma  Xi  1919. 

Research  Assistant  in  Zoology,  University  of  Illinois  1919-1920. 

Elected  to  membership  in  Kappa  Delta  Pi  1920. 

Student,  Marine  Biological  Laboratory,  Woods  Hole,  Mass. 
Summer  1920. 

Fellow,  University  of  Illinois  1920-1921. 

PUBLICATIONS: 
Two  new  monostomes  from  Asia.  Jour.  Parasit.  (in  press). 


AN     INITIAL     FINE    OF    25     CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $I.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


MAR  4   1933 


FEB  1  2  1940 
JAN  24  1950 
JUL  19  fl50 
OCT  181950 


•?-/&- 


LD  21-50m-l,'33 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


